Reorder dockerfile to optimize rebuilds

[justinbot]

Optimizes docker image rebuilds following a code change, by installing dependencies before copying code so those layers can be cached. This speeds up cycles of build image -> code change -> build image again.

In my local testing, it's about 60s faster:

Before

No layers cached

[+] Building 186.4s (22/22) FINISHED
 => [internal] load build definition from Dockerfile                                                                                                   0.0s
 => => transferring dockerfile: 37B                                                                                                                    0.0s
 => [internal] load .dockerignore                                                                                                                      0.0s
 => => transferring context: 34B                                                                                                                       0.0s
 => [internal] load metadata for docker.io/library/node:16-slim                                                                                        0.2s
 => [internal] load metadata for docker.io/library/node:16                                                                                             0.2s
 => [internal] load build context                                                                                                                      0.0s
 => => transferring context: 20.92kB                                                                                                                   0.0s
 => CACHED [stage-1 1/8] FROM docker.io/library/node:16-slim@sha256:34a3b4b7c2704ce52372c42b9b7945b41fe8eb98d74e8af472add0b599b6e1ff                   0.0s
 => CACHED [builder 1/8] FROM docker.io/library/node:16@sha256:1ed1e17ccabb09038cfb8a965337ebcda51ef9e9d32082164c502d44d9731a02                        0.0s
 => [builder 2/8] COPY . /src                                                                                                                          0.1s
 => [builder 3/8] WORKDIR /src                                                                                                                         0.0s
 => [builder 4/8] RUN curl https://sh.rustup.rs -sSf | sh -s -- -y --profile minimal                                                                  11.2s
 => [builder 5/8] RUN apt-get update && apt-get install -y build-essential cmake                                                                       3.8s
 => [builder 6/8] RUN yarn --ignore-scripts --pure-lockfile                                                                                           23.1s
 => [builder 7/8] RUN node node_modules/esbuild/install.js                                                                                             0.2s
 => [builder 8/8] RUN yarn build                                                                                                                     115.9s
 => [stage-1 2/8] COPY --from=builder /src/lib/ /bin/matrix-hookshot/                                                                                  0.0s
 => [stage-1 3/8] COPY --from=builder /src/public/ /bin/matrix-hookshot/public/                                                                        0.0s
 => [stage-1 4/8] COPY --from=builder /src/package.json /bin/matrix-hookshot/                                                                          0.0s
 => [stage-1 5/8] COPY --from=builder /src/yarn.lock /bin/matrix-hookshot/                                                                             0.0s
 => [stage-1 6/8] WORKDIR /bin/matrix-hookshot                                                                                                         0.0s
 => [stage-1 7/8] RUN yarn --ignore-scripts --production --pure-lockfile && yarn cache clean                                                          22.9s
 => [stage-1 8/8] COPY --from=builder /src/node_modules/@turt2live/matrix-sdk-crypto-nodejs /bin/matrix-hookshot/node_modules/@turt2live/matrix-sdk-c  2.6s
 => exporting to image                                                                                                                                 3.8s
 => => exporting layers                                                                                                                                3.8s
 => => writing image sha256:8cbb1cdcf359c5fe20a9d00516a2a2590ef4a579f02250c8766df7c447dfde01                                                           0.0s
 => => naming to docker.io/library/hookshot                                                                                                            0.0s

After

All cached except build steps

[+] Building 124.2s (22/22) FINISHED
 => [internal] load build definition from Dockerfile                                                                                                   0.0s
 => => transferring dockerfile: 37B                                                                                                                    0.0s
 => [internal] load .dockerignore                                                                                                                      0.0s
 => => transferring context: 34B                                                                                                                       0.0s
 => [internal] load metadata for docker.io/library/node:16-slim                                                                                        0.2s
 => [internal] load metadata for docker.io/library/node:16                                                                                             0.2s
 => [internal] load build context                                                                                                                      0.0s
 => => transferring context: 20.92kB                                                                                                                   0.0s
 => [stage-1 1/7] FROM docker.io/library/node:16-slim@sha256:34a3b4b7c2704ce52372c42b9b7945b41fe8eb98d74e8af472add0b599b6e1ff                          0.0s
 => [builder 1/9] FROM docker.io/library/node:16@sha256:1ed1e17ccabb09038cfb8a965337ebcda51ef9e9d32082164c502d44d9731a02                               0.0s
 => CACHED [builder 2/9] RUN curl https://sh.rustup.rs -sSf | sh -s -- -y --profile minimal                                                            0.0s
 => CACHED [builder 3/9] RUN apt-get update && apt-get install -y build-essential cmake                                                                0.0s
 => CACHED [builder 4/9] WORKDIR /src                                                                                                                  0.0s
 => CACHED [builder 5/9] COPY package.json yarn.lock ./                                                                                                0.0s
 => CACHED [builder 6/9] RUN yarn --ignore-scripts --pure-lockfile                                                                                     0.0s
 => [builder 7/9] COPY . ./                                                                                                                            0.1s
 => [builder 8/9] RUN node node_modules/esbuild/install.js                                                                                             0.3s
 => [builder 9/9] RUN yarn build                                                                                                                     114.8s
 => CACHED [stage-1 2/7] WORKDIR /bin/matrix-hookshot                                                                                                  0.0s
 => CACHED [stage-1 3/7] COPY --from=builder /src/yarn.lock /src/package.json ./                                                                       0.0s
 => CACHED [stage-1 4/7] RUN yarn --ignore-scripts --production --pure-lockfile && yarn cache clean                                                    0.0s
 => [stage-1 5/7] COPY --from=builder /src/node_modules/@turt2live/matrix-sdk-crypto-nodejs /bin/matrix-hookshot/node_modules/@turt2live/matrix-sdk-c  2.4s
 => [stage-1 6/7] COPY --from=builder /src/lib ./                                                                                                      0.0s
 => [stage-1 7/7] COPY --from=builder /src/public ./public                                                                                             0.0s
 => exporting to image                                                                                                                                 3.9s
 => => exporting layers                                                                                                                                3.9s
 => => writing image sha256:ff21d735d4823e80b08bd78aa4fa00b93d2047886f14a2ff1b3128cb7eeeddea                                                           0.0s
 => => naming to docker.io/library/hookshot                                                                                                            0.0s

[Half-Shot]

Looks fine to me. Thank you for doing the research into it!