Merge changes Id942c20c,Idd286bea,I8917a26e,Iec8c3477,If3c25dcd, ... into integration

* changes:
  feat(cpufeat): enable FEAT_PAuth to FEAT_STATE_CHECKED
  perf(cpufeat): centralise PAuth key saving
  refactor(cpufeat): convert FEAT_PAuth setup to C
  refactor(cpufeat): prepare FEAT_PAuth for FEATURE_DETECTION
  chore(cpufeat): remove PAuth presence checks
  feat(cpufeat): enable FEAT_BTI to FEAT_STATE_CHECKED