Wrap the escrow data with key from keystore

Factor out a class to handle the aes encrypted blob, and
further encrypt the reboot escrow data with a local key
from key store.

Bug: 172780686
Test: atest FrameworksServicesTests:RebootEscrowDataTest \
            FrameworksServicesTests:LockSettingsServiceTests \
            FrameworksServicesTests:RecoverySystemServiceTest \
            FrameworksServicesTests:RebootEscrowManagerTests ;
      atest CtsAppSecurityHostTestCases:ResumeOnRebootHostTest
Change-Id: Id0e18bef4d3b194a254fa1755cd17a43a7b6e5bc