Update on "[FX] Make wrapped functions traceable"

This patch does two things:
1. For the purpose of introspecting arguments, this patch adds a call to `inspect.unwrap` to unwrap any layers of `functools.wraps` decorators on the function. This is similar to what `inspect.signature` is doing as well. This allows for functions/methods with wrapping decorators applied to them to be traced
2. Fixes a poor error message where a variadic method without an explicit `self` argument was trying to be traced. I elected to just throw in this case for now. Conceptually we could support this but I was running into some weird correctness issues and I think that's better addressed in a follow-up PR.

Closes #46665

Differential Revision: [D24465958](https://our.internmc.facebook.com/intern/diff/D24465958)

[ghstack-poisoned]

test/test_fx.py

@@ -117,12 +117,12 @@ def forward(self, *args, **kwargs):
 
     def test_args_kwargs_no_self(self):
         class T(torch.nn.Module):
-            def forward(*args, **kwargs):
+            def forward(*args, **kwargs):  # noqa: B902
                 self = args[0]
                 return torch.relu(args[1])
 
         t = T()
-        with self.assertRaisesRegex(RuntimeError, 'cannot be part of \*args expansion'):
+        with self.assertRaisesRegex(RuntimeError, r'cannot be part of \*args expansion'):
             self.checkGraphModule(t, (torch.rand(1), torch.rand(1)), {'foo': torch.rand(1)})
 
     def test_fx_shifts(self):