Refactor compiler

[rtsao]

Summary

• Replaces vanilla babel-loader with simplified version which also caches static analysis metadata in lockstep with the transformed code. This eliminates the current brittleness with translations discovery (related to persistent cache invalidation) and removes the need for hacky workaround fixes in Fix i18n hydration on dev restart #442 and Fix i18n discovery on dev restart #434.
• Replaces our forked file-loader with a vastly simpler version that doesn't rely on singletons or shared state.
• Replaces chunk id loader with a version that doesn't rely on singletons.
• Simplifies Babel configuration
• Deletes a considerable amount of vestigial code (mostly relating to the original evergreen bundles implementation and replaced test functionality)
• Adds proper dev mode configuration to react babel preset.

Webpack compilation/loader communication

The old pattern relied on shared state via singletons which was far from ideal. This has been replaced with usage of loader context (and plugins that provide/consume this context). Shared state (between compilations and loaders as well as between sibling compilations) is now instantiated, passed, and mutated in a much more explicit manner.

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Resolves #7
Resolves #8
Resolves #9
Resolves #15
Resolves #47

Lays the groundwork for #393 #426 fusionjs/rfcs#7 fusionjs/rfcs#10

[KevinGrandon]

Going to stamp this for now, but might be nice to run through some of this with you later today or next week.