### Description

* Moves the logic of creating chunks from ChunkItem implementators to
ChunkType.
* Collect chunk items during chunk_group instead of per chunk
* Removes the optimization and produce optimized chunks in the first
pass, by splitting them according to heuristics
  * Aims for chunk size between 30k and 300k
  * App and Vendors code is separated
  * node_modules with different package names are separated 
  * code is separated by folder structure
* Makes Code Generation independent of chunk group
* removes recursive is_async in favor of determining the async module
state during chunk group creation.

### Testing Instructions

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Closes WEB-1771

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Co-authored-by: Justin Ridgewell <justin@ridgewell.name>