[aot autograd] merge all outputs of funtionalization analysis into single metadata (#95991)
This makes the next PR in the stack cleaner: having the top level entry point to aot autograd perform the functionalization analysis pass once, and plumb the metadata everywhere else that we need it.
I put it in a separate PR because I recently learned that this function is used in fbcode, so I'll need to fix up internals when I land this PR.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/95991
Approved by: https://github.com/ezyang
