Move ownership of type system entities to CompilerTypeSystemContext

[MichalStrehovsky]

Type system entities that produce code or EETypes need to be owned by the CompilerTypeSystemContext so that we can match/reconcile them between the scanning and code generation phases.

This includes

• Reflection invoke stubs
• Various interop types and methods

We currently e.g. can't do fixed slot assignments to virtual methods on interop's delegate wrappers. Similar problems will arise for e.g. reflection invoke stubs and their generic dictionary layout (once we start inlining generic dictionary lookups).

[MichalStrehovsky]

When resolving this bug, look for the issue number in the sources. We have some workarounds in place.