v2024.05.06.00

Change `result_of` to `invoke_result` in watchman/Result.h

Summary: C++20 has [eliminated](https://en.cppreference.com/w/cpp/types/result_of) `result_of` in favour of `invoke_result`. It's mysterious that this code even still works, but, nevertheless, I'm fixing it.

Differential Revision: D56987484

fbshipit-source-id: e1e641424271e1164eee19be5726ec6abe0c1ffd