[torch.fx.wrap] Use callable / function.__name__ instead of function.__code__.co_name (#84373)
Ran across this issue while using torch.fx.wrap on a decorated function: it triggered a KeyError: 'wrapper_inside_decorator'. torch.fx.wrap stores function.__code__.co_name, but that isn't set correctly (and doesn't match it's name in the global namespace) for decorators; function.__name__ is set correctly.
Also adjusted to checking for callable instead of checking for the existing of __code__ to allow for a broader variety of functions that can be passed in. Eg. using functools.cache returns a callable that won't have a __code__ attribute.
I added a unit test (that incidentally fails every test in the suite before the fix commit -- because it affects the global state), and then a fix that addresses it.
```
In [1]: import functools
In [2]: def decorator(f):
...: @functools.wraps(f)
...: def wrapper(*args, **kwargs):
...: return f(*args, **kwargs)
...: return wrapper
...:
In [3]: @decorator
...: def some_function(x):
...: return x
...:
In [4]: some_function.__name__
Out[4]: 'some_function'
In [5]: some_function.__code__.co_name
Out[5]: 'wrapper'
```
Pull Request resolved: https://github.com/pytorch/pytorch/pull/84373
Approved by: https://github.com/jamesr66a, https://github.com/SherlockNoMad
