[clang] [AArch64][FMV] Enable PAuth and BTI hardening of resolver functions (PR #141573)

[Anatoly Trosinenko via cfe-commits]

atrosinenko wrote:

I have rebased this PR onto current `main` branch and moved the new test to `AArch64/` subdirectory. There are no unresolved comments anymore, as far as I can see.

https://github.com/llvm/llvm-project/pull/141573