"Just in time" builds

[ggetz]

This is a followup from #10399

Refactors the build scripts a bit to allow for "just in time" compilation, a method we use in other projects for internal app development.

This allows a developer to run

npm install
npm start

without having to manually build, and everything should "just work".

This is done by revising server.cjs such that requests to Cesium.js or similar build artifacts will case rebuilding incrementally if a file has changed before serving the file contents.

• Factors out common build code from gulpfile.cjs into build.cjs
• Updates Build Guide to explain new preferred workflow
• Since this does not modify any of the build configuration itself from the last PR, just the workflow, there are no changes no the end user
• HelloWorld now uses unminified Cesium so it works during development builds without having to manually build.
• Removes file-level eslint ignores in server.js

• Merge Streamline build processes with esbuild #10399
• Cleanup build.js eslint errors
• Cleanup internal documentation
• Sandcastle jshint

[cesium-concierge]

Thanks for the pull request @ggetz!

• ✔️ Signed CLA found.
• ❔ CHANGES.md was not updated.
  • If this change updates the public API in any way, please add a bullet point to CHANGES.md.
• ❔ Changes to third party files were made.
  • Looks like a file in one of our ThirdParty folders (ThirdParty/, Source/ThirdParty/) has been added or modified. Please verify that it has a section in LICENSE.md and that its license information is up to date with this new version.

Reviewers, don't forget to make sure that:

• Cesium Viewer works.
• Works in 2D/CV.

[sanjeetsuhag]

@ggetz This is going to be a great quality of life update! I have a few initial comments.

[sanjeetsuhag]

I still got the following warning when running npm install:

npm WARN deprecated chokidar@2.1.8: Chokidar 2 does not receive security updates since 2019. Upgrade to chokidar 3 with 15x fewer dependencies

Looking at node_modules/chokidar/package.json, the version seems to indicate 3.5.3, so I don't know what's causing this. Do you see this same output when running the install step?

[ggetz]

This is not due to our immediate chokidar dependency. It's a fairly common package that others depend on as well.

You can run npm list --depth=[depth] to check the dependency tree.

In this case it looks like gulp@4.0.2 is the source of this warning. That's still the latest version unfortunately. We'll need to weigh if we want to stay will gulp, which is still a popular tool despite the lack of updates. Irregardless, that would be out of the scope of this PR.

[ggetz]

That @sanjeetsuhag! I've responded to all of your feedback.

[ggetz]

@sanjeetsuhag Can you take another look at this when you get the chance now that #10399 is merged?

[ggetz]

Thanks @sanjeetsuhag! I addressed your feedback.

[sanjeetsuhag]

This looks good. Thanks @ggetz!