Add setActiveUser to BiometricManager/Service

On devices with multiple biometrics, ConfirmCredentials can
potentially ask the user to authenticate using more than one
biometric. This is a wrapper that sets the active user for
all modalities.

Bug: 111461540

Test: With work profile set up, CC has same behavior as
      device running P.
      1) With one lock disabled, use modified BiometricPromptDemo
         to authenticate using CC in the work version of the app
      2) Go to normal version of the app, authenticating
         using BP (not CC) works with non-work biometric

Change-Id: I04b6f64d3fe373269366c243f406d897cb6fd83a