[llvm] [clang] [lld] [clang-tools-extra] [lld][AArch64][ELF][PAC] Support AUTH relocations and AUTH ELF marking (PR #72714)

[Daniil Kovalev via cfe-commits]

kovdan01 wrote:

- Addressed the review comments except https://github.com/llvm/llvm-project/pull/72714/#discussion_r1423345089 (I'll submit a subsequent commit addressing that shortly).
- Fixed merge conflict appeared after #77300, see a021f15540300e032446825de805143f0f6214c4.


https://github.com/llvm/llvm-project/pull/72714