Resetting widget cache when some configurations change

Sometimes widget providers hardcode colors in their remoteViews
by loading them from resources. On UI mode change, this can lead to
inconsistent UI if some widgets use a different configuration
than others.

Test: Verified with calendar widget on device
Bug: 133064045
Change-Id: If47a6b1973f55b7590f5d4116813d6a332951697