Migrate all plugin-related functionality into BscPlugin

There are several items in brighterscript that are not currently contained within the BscPlugin that are part of the plugin system. Should apply to every plugin event possible, so we're fully utilizing the plugin system and enabling other plugins to do more advanced features.

For example, afterProgramCreate, once we add #1552 , should move the actual program construction into the BscPlugin itself. This would lend itself to allowing even more flexibility to the plugin system to provide the instance of the program itself (maybe for caching or subclassing).

Requirements:

• move every applicable plugin code into the BscPlugin instead of being hardcoded inside Program or Scope or wherever.
• enhance the plugin events to include the contributed features. For example, createProgram should have a .program prop that is set when a plugin creates the program (normally will be BscPlugin).