[dynamo] Forward OptimizedModule.__setattr__ to the wrapped module (#122098)
Fixes #114844
In the linked issue we have
```
compiled_module = torch.compile(module)
compiled_module.x = ...
compiled_module(...) # Mutates self.x
```
Where since the module mutates `self.x` you would expect `compiled_module.x`
to be updated but actually `compiled_module.x = ...` sets an attribute "x"
on the `OptimizedModule` object while the forward method of the module mutates
`module.x`.
This gives the expected behavior by forwarding `compiled_module.__setattr__`
down to `module.__setattr__`. There is already a corresponding `__getattr__`
so now `compiled_module.x` becomes an alias for `module.x`.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/122098
Approved by: https://github.com/ezyang, https://github.com/lezcano
