Add getThemedResourcesForApplicationAsUser()

Change-Id: I90b7cb441e4056f59b7260ffa55e31eba644e25a
Support theming navbar separately from SystemUI
This allows using a different theme for the navbar than the theme
applied to the rest of SystemUI.  This will not affect theming until
we have the front end in place that allows users to change this.

Change-Id: I3ad4e8774ac69d1e6e1d83fa5e1ffe59b977d4e9