Add KeyPurpose::ATTEST_KEY. am: 7c13039711 am: 99ac9848df am: cad4604a2e am: 0a21d6ecb6

Original change: https://android-review.googlesource.com/c/platform/hardware/interfaces/+/1534063

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: I6d43a009db80d1008d0637abc2b1b547bb871255