[llvm] [BOLT][AArch64] Implement PLTCall optimization (PR #93584)

[Paschalis Mpeis via llvm-commits]

paschalis-mpeis wrote:

Rebased to latest main and addressed latest review.

---

NOTE: some unrelated commits on main were causing failures on unrelated BOLT tests.
Now that tests seem OK, I was able to do the rebase.

Those commits were:
- Errors introduced by:
  - 435ea21c897f
  - 20d497c26fc
- Fixed by:
  - 0353f6a
  - 6ef632a
  - #94301


https://github.com/llvm/llvm-project/pull/93584