[llvm] [hwasan] Add intrinsics for fixed shadow on Aarch64 (PR #89319)

[Vitaly Buka via llvm-commits]

https://github.com/vitalybuka approved this pull request.

LGTM
up to @fmayer if we need error message on `!.has_value()`

https://github.com/llvm/llvm-project/pull/89319