Use KmErrorOr<T> for key blob auth encryption

This is an interface-only change that makes key blob auth encryption
easier to work with, and -- more importantly -- ensures that errors
are checked, since KmErrorOk will crash the process if an error is
left unchecked.

Bug: 187105270
Test: keymaster_tests
Change-Id: I9e919d0d29714d370357545958625bb7b3f7a9e4
Merged-In: I9e919d0d29714d370357545958625bb7b3f7a9e4
5 files changed