Fix c10::util::get_fully_qualified_type_name for MSVC (#31313)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/31313
This is a bugfix. The reason we couldn't enable the constexpr-ness for it before is that it was buggy,
and without constexpr it crashed at runtime and not at compile time which seems to have passed our CI unfortunately...
ghstack-source-id: 96380160
Test Plan: Now it works even when enabling constexpr for it
Differential Revision: D19087471
fbshipit-source-id: 28be107389f4507d35d08eab4b089a405690529b
