Add attestation key to generate/import messages. am: 6e20ea4592 am: c1cdf4c457

Original change: https://android-review.googlesource.com/c/platform/system/keymaster/+/1535583

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: I20f98924be00448be82e6a06e9b65f3012ca56bf