Handle more cases in Completion_lib.Records.resolve_record_type

We currently handle T_record and T_variable in Completion_lib.Records.resolve_record_type, but some cases that should be handled like T_for_all, T_abstraction, and possibly T_app, are missing. We should handle them.

Acceptance criteria

• Missing cases are handled.
• It might be nice to avoid using _ there in case new constructors are added.
• Tests added.