Unify management of thread local settings (#35523)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/35523
In this PR we extend ThreadLocalState to cover dispatch keys and
ThreadLocalDebugInfo and move it from JIT interpreter down to
thread management (at::launch) and autograd (backward threads) code
Test Plan: unit tests (CI)
Reviewed By: dzhulgakov
Differential Revision: D20615714
fbshipit-source-id: 16a9fc96a25cb6c2629230b1187fbf78786ac565
