feat: v2 of the closure serializer

[sam-goodwin]

Total re-write of the closure serializer as a single recursive pass.

For visual context, refer to this diagram of Prototypical Inheritance:

Outstanding tasks:

• support recursive references in properties
• serialize classes as Functions (not classes)
• detect augmented globals
• detect references to modules or a module's exports and emit as an import/require
• run esbuild on the serialized closure + imports to create a tree-shaken bundle with minimal usage of the closure serializer and maximal usage of esbuild

[sam-goodwin]

Still working out the exact algorithm, but making great progress thanks to this visualization.