[inductor] Refactor cpp_wrapper to be an attribute of GraphLowering (#97709)
Summary: to prepare for further AOT Inductor changes
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### <samp>🤖 Generated by Copilot at 7dff885</samp>
This pull request adds support for AOT compilation and C++ wrapper code generation for inductor models. It modifies the `GraphLowering` class in `torch/_inductor/graph.py` and the `compile_fx` function in `torch/_inductor/compile_fx.py` to enable this feature.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/97709
Approved by: https://github.com/jansel
