Allow LockscreenCredential to represent any proposed credential am: 8c9ac5c0dc am: bfea325f67 am: 38dbc5d526 am: 0b4f60c4ec

Original change: https://android-review.googlesource.com/c/platform/frameworks/base/+/2775375

Change-Id: Ifa2da005d7893b5f3e44812a605090d225edd29d
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>