Notification color fixes

* Change Notification.isColorized() to return false if the given color is COLOR_DEFAULT.  This removes an odd, inconsistent, and likely unused state.
* Remove config_tintNotificationsWithTheme which we're not going to be using to reduce the color palette complexity.
* Change ensureColors() to use the theme's primary/secondary text colors.
* Numerous simplifications in logic that fall out from these changes.

Bug: 181048615
Test: atest NotificationComparatorTest NotificationTest AppOpsCoordinatorTest NotificationGutsManagerTest NotificationManagerServiceTest NotificationBuilderTest
Change-Id: Ie49cc9f3f9ea01685ae026587e2d1cdb96391eb2