Implement GetRootOfTrust

Bug: 219076736
Test: VtsAidlKeyMintTargetTest
Change-Id: I8485360f253ca20f008c5df5090e79c1781fbb4f
Merged-In: I8485360f253ca20f008c5df5090e79c1781fbb4f
Ignore-AOSP-First: already present in aosp/master
4 files changed