[clang] -fsanitize=function: fix MSVC hashing to sugared type (PR #66816)

[Matheus Izvekov via cfe-commits]

mizvekov wrote:

Okay, makes sense, although we can only say for certain regarding in-tree users.

I have gone ahead and done that, plus I have renamed `mangleTypeName` to `mangleCanonicalTypeName` so the name describes the behavior better, and since this is an API break, we break it loudly.

https://github.com/llvm/llvm-project/pull/66816