Support special TypeAlias in Python

[oxisto]

There seems to be a special class TypeAlias, which can be used to denote that something is a type alias. We should see how we can support this, because this is used all over the place in typings files.

FileDescriptor: TypeAlias = int  # stable

See https://docs.python.org/3/library/typing.html#typing.TypeAlias

[oxisto]

You gotta love python, this was introduced in 3.10 and is already deprecated since 3.12, but "it's not going away". Now there is a "type" keyword (which is the better option I think): https://docs.python.org/3/reference/simple_stmts.html#type