Add Framework APIs for Identity Credential.

The Identity Credential APIs provides an interface to a secure store
for user identity documents.  These APIs are deliberately fairly
general and abstract.  To the extent possible, specification of the
message formats and semantics of communication with credential
verification devices and Issuing Authorities (IAs) is out of scope for
these APIs.

The Identity Credential APIs rely on user authentication to protect
data elements in credentials which is implemented through
auth-tokens. This CL contains changes to CryptoObject to allow this.

Bug: 111446262
Test: CtsIdentityTestCases
Change-Id: I48f21a561b762d86c9ca8d229962782572412f47