Summary:
Enabling Metro cache for dev mode. For release builds we reset the cache.
Cache is used for faster compilation in dev mode for both main and renderer bundles, as well as for plugins.
Currently we have few side effects based on env vars, so cache is invalidated when they are changed. Also the cache is invalidated when transformations are changed (changed code, bumped dependency etc). Also added a script to reset the cache if something is going wrong.
Reviewed By: mweststrate
Differential Revision: D20691464
fbshipit-source-id: 478947d438bd3090f052dbfa6ad5c649523ecacb
da7449c20b