[SR][Code cleanup] Typedef/default for kwargs (#69164)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/69164
We have lots of methods that take `std::unordered_map<std::string, c10::IValue>` now. That's kind of ugly and cumbersome to type, so add a `KWargs` typedef.
Also made the `operator()` default `kwargs` to empty. Note that we could have another overload that doesn't take `kwargs` at all, but the perf gain is so minuscule it's probably not worth it.
ghstack-source-id: 144691899
Test Plan: CI
Reviewed By: d1jang
Differential Revision: D32734677
fbshipit-source-id: 8d6496a6d1ec2dc71253151d2f6408f1387966cf
