[LLDB] NativeThreadLinux invalidate register cache on stop

In our discussion D79699 SVE ptrace register access support we decide to
invalidate register context cached data on every stop instead of doing
at before Step/Resume.

InvalidateAllRegisters was added to facilitate flushing of SVE register
context configuration and cached register values. It now makes more
sense to move invalidation after every stop where we initiate SVE
configuration update if needed by calling ConfigureRegisterContext.

Reviewed By: labath

Differential Revision: https://reviews.llvm.org/D84501