non-strict improvements: constant args and kwargs (#119529)
This PR makes a couple of improvements to non-strict to bring it closer to strict. (This lets us remove some expected failures from test_export.)
1. Support constant arguments (easy).
2. Support keyword arguments. This forces us to add kwargs to `aot_export_module`. Indeed there is no way to make this work otherwise, because some arguments in a function signature can be keyword-only and thus cannot be simulated by positional arguments alone. Adding kwargs to `aot_export_module` turns out to be fairly routine, but there is a bit of a unsatisfactory fork between how it is called by strict and non-strict: because strict calls it on a graph module, kwargs must be converted to positional arguments. So kwargs in `aot_export_module` really only comes into play in non-strict.
Differential Revision: D53600977
Pull Request resolved: https://github.com/pytorch/pytorch/pull/119529
Approved by: https://github.com/zhxchen17, https://github.com/tugsbayasgalan
