By moving AsyncCompile to its own file, we can import codecache without running the side effects of AsyncCompile. This will be important for AOTAutogradCaching, where we want to share some implementation details with codecache.py without spawning new processes.
To conservatively maintain the same behavior elsewhere, every time we import codecache, I've added an import to torch._inductor.async_compile (except in autograd_cache.py, where the explicit goal is to not do this)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/127235
Approved by: https://github.com/aorenste, https://github.com/oulgen, https://github.com/masnesral
