[AArch64][PAC] Support BLRA* instructions in SLS Hardening pass (#98062)
Make SLS Hardening pass handle BLRA* instructions the same way it
handles BLR. The thunk names have the form
__llvm_slsblr_thunk_xN for BLR thunks
__llvm_slsblr_thunk_(aaz|abz)_xN for BLRAAZ and BLRABZ thunks
__llvm_slsblr_thunk_(aa|ab)_xN_xM for BLRAA and BLRAB thunks
Now there are about 1800 possible thunk names, so do not rely on linear
thunk function's name lookup and parse the name instead.
This patch reapplies llvm/llvm-project#97605.