This change adds the @RequiresFeature annotation to Ikev2VpnProfile Builder methods, and checks before provisioning VPN profiles. Bug: 156681625 Test: New tests added, passing. Change-Id: I125d8fbe5d67fb877ad7d0636c007cb3e1a9f59b Merged-In: I125d8fbe5d67fb877ad7d0636c007cb3e1a9f59b (cherry picked from commit e84a17dd1706f4c8373047b2023a1ec4b7cf4bf3)