Implement uid/namespace clearing for Keystore 2.0.
Test: Verified that keys get deleted when an app gets uninstalled.
Change-Id: I1b0b65e977177a6e34c500b00b5070ec18be2671
This CL introduces the client side for IKeystoreUserManager aidl and
integrates it with the LockSettingsService.
Bug: 171305115
Test: TBD
Change-Id: I7560e98f95aaec6b85cdcfc01ba83aea0ccc52ae