identity: Add support for ECDSA auth and don't require session encryption. am: 55f62fc125 am: 6b8617ce9c

Original change: https://android-review.googlesource.com/c/platform/frameworks/base/+/2241164

Change-Id: Iec4121daaaa0ac9eaeb16d44ebc6f0dba2dcb505
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>