Rollup plugin is a leaky abstraction

[thescientist13]

Been thinking about how we support a rollup plugin, which to me feels like a leaky abstraction. I say that because this is generally used to configure Rollup to handle non-JS things, like JSON or TypeScript but we already have a Resource plugin that can do that in development, so why not for Rollup too? 🤔

This is currently being handled in some cases already (I think) so not sure if this just my naivety around how Rollup works, but it would be nice to at least harmonize this since it feels like a duplication of effort in some ways.

[thescientist13]

Might also want to loop in the following?

• remove local development symlink workaround from rollup.config.js #623

Also, even after #971 and being able to drop a bunch of Rollup plugins the API is still needed for some of the following exceptions

1. Babel - @rollup/plugin-babel
2. GraphQL - @rollup/plugin-alias
3. CommonJS - @rollup/plugin-commonjs / @rollup/plugin-stream

Also, could / should we defer .js files to Greenwood resources too?