[Distributed Autograd] Make debugInfoMap from strings to ints (#38416)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/38416
This diff primarily changes the `debugInfoMap` to map from strings to ints, instead of strings to strings. We were basically just converting these back to ints in Python so this avoid the extra conversions.
`arc lint` also exposed tons of linting issues so fixing those here as well.
Test Plan: Build Bot - the tests already check whether the debugInfoMap is correct.
Differential Revision: D21266522
fbshipit-source-id: e742dec272bb1bab1bee01542610802922abab6b
