Use a bundler to simplify the deployment

[eine]

By using a bundler, such as webpack, the deployment can be reduced to three files: main.js, action.yml and README.md. See, for example: https://github.com/1138-4EB/issue-runner/tree/gha-tip

[Ecco]

I'm not sure I see the point of this. There are already very few files anyway.

Also I think the fewer tools we use the easier it is for newcomers to contribute 😄

[eine]

I'm not sure I see the point of this. There are already very few files anyway.

Are you sure? There are currently ~275 files (14.3MB) in the release, and the relevant files account for 3.15KB. It is true that it is a low number for a typical JavaScript application. However, the JS ecosystem being so bad-performing shouldn't prevent us from being kind with bandwidth and disk usage. Moreover, the current list of files is subject to change (content of node_modules), which makes maintaining the project harder.

Also I think the fewer tools we use the easier it is for newcomers to contribute 😄

Note that #5 is based on ncc precisely because that's the bundler suggested/explained in the docs of GitHub Actions: https://help.github.com/en/articles/creating-a-javascript-action#commit-and-push-your-action-to-github

Nonetheless, newcomers can ignore this feature completely. This is only relevant for deployment/releases. Therefore, only maintainers need to be aware of it. Developers who are not maintainers can still execute node main.js just as they execute node index.js now. Furthermore, including this feature in the codebase does not mean you need to use it. I.e., you can keep the same sources and deploy either unbundled, bundled or both of them.

[eine]

I'm closing this because #5 (which is part of eine/setup-msys2) has been tested for some months and it works as expected.