[clang] [lld] [lld][ELF][clang][MTE] Add generic -z memtag-* options (PR #187055)

[Fangrui Song via cfe-commits]

https://github.com/MaskRay requested changes to this pull request.

I almost did not notice this patch as I am not added a reviewer. The clang change makes sense but can you extract the lld/ELF to a separate patch?

* lld: Add -z memtag-{mode,heap,stack}
* clang: Switch -fsanitize=memtag to use -z memtag-* linker flags

https://github.com/llvm/llvm-project/pull/187055