Support FunctoolsPartialVariable::get_function, fix NamedTupleVariable::as_proxy and handle call_function in get_fake_values_from_nodes (#119435)
partially address https://github.com/pytorch/pytorch/issues/118785
This diff fixes three things:
1. add get_function to FunctoolsPartialVariable note that it will be available only if all args constant otherwise,
it would throw unimplemented in the call to asPythonConstant.
2. NamedTupleVariable takes args dispatched not as list ex: NamedTuple(a, b, c) vs NamedTuple([a, b, c]),
hence fix that by specializing asProxy.
3. A call to create_arg from within create_proxy, changes a python NamedTuple to a function call node without
associating an example value! Updated get_fake_values_from_nodes to handle such case.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/119435
Approved by: https://github.com/jansel, https://github.com/anijain2305
ghstack dependencies: #119314
