Callable object custom signatures are resolved incorrectly

What's the issue?

typing.get_type_hints supports callable objects with custom signature definitions (__call__ + __signature__).

Running get_type_hints on obj.__call__ instead of obj breaks that, and that's exactly what happened here.

The entire obj should be passed along and special cased for #18092 elsewhere. Sadly, the warning was not there when this was added.

What did you expect to happen?

obj.__signature__ to be used, rather than the raw signature of obj.__call__, which cannot be overwritten in any reasonable way.

How to reproduce?

def custom_signature(my_resource: MyResource) -> dg.MaterializeResult: ...

class MyWrapper():
  def __init__(self, fn: Callable[..., Any]) -> None:
    self.__signature__ = inspect.signature(custom_signature) # <- this is the signature I set
    
  def __call__(self, **kwargs: Any) -> Any: ... # <- this signature is used

my_resource will be interpreted as an "input", because it fails being recognized as a resource, due to missing type information.

Current behavior (get_type_hints(fn.__call__)):

{'kwargs': typing.Any, 'return': typing.Any}

Correct behavior (get_type_hints(fn)):

{'my_resource': <class 'my_project.MyResource'>, 'return': <class 'dagster._core.definitions.result.MaterializeResult'>}

Dagster version

1.11.15

Deployment type

Dagster Cloud

Deployment details

Irrelevant

Additional information

Broken in #18092

I'm aware Dagster has it's own get_type_hints wrapper, but passing the correct value there should fix this at least.

This is required for wrappers, which pass along dependencies from functions they're wrapping.

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