Use type hints to link function arguments and annotated assignment

[felix-hilden]

We should use function type hints to link argument usage. For example:

def foo(bar: Thing):
    bar.method  # links to Thing.method

I'm 90 % sure this isn't a thing yet.

[felix-hilden]

The same should apply with annotated assignment:

a: Thing = b
a.method

[felix-hilden]

Some complications arise from us not executing the parsed code though. VS importable module code, which allows us to resolve string type hints and navigate hints conveniently.

One way we could limit this, would be to only accept single, direct types. Meaning no Optional/Union/List or other generics. But we'd have to recognise these hints somehow, because resolving the complex hints (i.e. taking their instance) leads to warnings down the line when the value is used. Because we don't handle subscripts, though, I think we're in the clear. A hypothetical attempt at resolving Union[A, B]().method would not produce links because the subscript stops our resolving. But I'll have to think about this some more.