Feature: Recursive type aliases

[yangdanny97]

We probably need to change the way we represent type aliases to be more like classes, to handle recursive aliases. Right the aliased type is stored inline, making recursion impossiblel; all recursive references are treated as Unknown

Ideally we could just have TypeAlias store a unique identifier, and look up the aliased type somewhere else. This would be similar to how we have a ClassType and use it to look up the ClassMetadata