[dynamo][inductor] Provide public API to get compiler options/configs (#105026)
issues resolved: https://github.com/pytorch/pytorch/issues/101832
**context**: get torch.compile config for further usage. E.g, the training platform wants to get if model is compiled with cudagraph enabled and trigger further action
**how it is implemented**
* the core logic is backend.get_compiler_config() in torch/_dynamo/eval_frame.py
* for backend='inductor' / _TorchCompileInductorWrapper, we have inductor-specific implementation in get_compiler_config in torch/_inductor/compile_fx.py and torch/__init__.py
**how to use it**: Below is an example.
```
model = DummyModule()
optimized_module = torch.compile(
model, options={"triton.cudagraphs": True}
)
compiler_config = optimized_module.get_compiler_config()
if compiler_config["triton.cudagraphs"]:
pass
```
Pull Request resolved: https://github.com/pytorch/pytorch/pull/105026
Approved by: https://github.com/yanboliang, https://github.com/jansel
