[AArch64] FMV support and necessary target features dependencies.

This is Function Multi Versioning (FMV) implementation for AArch64 target in
accordance with Beta Arm C Language Extensions specification
https://github.com/ARM-software/acle/blob/main/main/acle.md#function-multi-versioning
It supports new "target_version" function attribute and extends existing
"target_clones" one. Also missing dependencies for target features were added.

Differential Revision: https://reviews.llvm.org/D127812