[LLDB] Add support for Arm64/Linux dynamic register sets

This is patch adds support for adding dynamic register sets for
AArch64 dynamic features in LLDB. AArch64 has optional features like
SVE, Pointer Authentication and MTE which means LLDB needs to decide
at run time which registers it needs to pull in for the current
executable based on underlying support for a certain feature.

This patch makes necessary adjustments to make way for dynamic
register infos and dynamic register sets.

Reviewed By: labath

Differential Revision: https://reviews.llvm.org/D96458