[Swift Bindings] Adding information about closed generics to the type database

[jkurdek]

When processing a module we can encounter closed generics as fields or arguments. The generic type might belong to the same module or other module. We need to process the newly encountered closed generic (maybe calculate some data like size, alignment, blittability) and save it into type database.

1. Keep track of newly encountered closed generics during ABI parsing
2. Process types in post-processing step and save it into type database

The problematic part is saving a new closed instance of a generic type coming from a different module into type database. Assuming that we process module by module we either have to load up a type database from a previously processed module and store the closed generic instance there or stick it on the database of the module we found it in.