Improve Dynamo support for torch function and class methods in general (#121365)
I was originally trying to solve https://github.com/pytorch/pytorch/issues/120799 but got sidetracked along the way.
This PR contains a couple fixes. Let me know if you want me to split them up!
- Properly handle invalid user code when "super()" is called from non-method/classmethod. It will now properly raise the same error as CPython
- Fix base VariableTracker `__str__` method shadowing all `__repr__` methods defined in subclasses
- Fix accessing a classmethod on a user object to bind "cls" and not "self"
- Fix custom class handling of super() call to properly handle mixed regular/class/static methods
Locally , test_repros.py -k test_batch_norm_act still fails where the generated graph module is:
```
Call using an FX-traced Module, line 8 of the traced Module's generated forward function:
x = self.forward(l_x_); self = l_x_ = None
x_1 = self.L__self___act(x); x = None
```
note that "self" is being unset on the first line even though it is used on the second one.
For reference, this is the test https://github.com/pytorch/pytorch/blob/c268ce4a6d7445d71637ad0d6cb88b94e52bb0a2/test/dynamo/test_repros.py#L1368-L1369
I cannot figure out where the generated forward function comes from though, any hint would be welcome!
Pull Request resolved: https://github.com/pytorch/pytorch/pull/121365
Approved by: https://github.com/jansel
