Bundle library using rollup

[lukasIO]

Initial motivation was #129 and that subsequently lead to

• use rollup as a bundler
• create a umd and esm bundle
• follow best practices for package.json entry files
• use babel (instead of tsc) for transpilation in order to target browser compatibility more specifically
• remove webpack and replace with rollup dev server for /example

some resources/projects used as inspiration:

• https://vitejs.dev/guide/build.html#library-mode
• https://github.com/davidcetinkaya/embla-carousel/tree/master/packages/embla-carousel
• https://github.com/mrdoob/three.js/tree/dev/utils/build
• https://levelup.gitconnected.com/code-splitting-for-libraries-bundling-for-npm-with-rollup-1-0-2522c7437697

The rollup build process started to show some warning around our protobuf.js dependency. Specifically some circular dependencies within that library and the frowned-upon usage of eval within the library.
Rollup seems to deal well with the circular dependencies, to workaround the usage of eval there are some annotations/additional context in rollup.config.js where basically every instance of eval gets replaced with undefined.

[lukasIO]

I removed the build-sample command (without dist present it was failing for me) but can re-add with a rollup equivalent if that command still makes sense/we want to continue to provide it

[davidzhao]

This is really fantastic. I'm reading about rollups and have learned something new today!

[davidliu]

So, something with rollup is screwing up react-native. Can't figure out what it is, but the javascript engine it's using doesn't like it. When debugging (which uses the computer's browser javascript engine), it works again.

For now, since react-native is still in alpha, I think we'll lock down the livekit-client versions that it can use until we figure out a more permanent solution.