[lld] [lld][AArch64][ELF][PAC] Support `.relr.auth.dyn` section (PR #96496)

[via llvm-commits]

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

LGTM from my point of view. I compared it with the original implementation in #87635 and confirm the empty and invalid `.rel.dyn` section in relocatable object file was fixed. 
Please wait for @MaskRay's approval before landing it.

https://github.com/llvm/llvm-project/pull/96496