Fix NIC colors not applying correctly

We need to re-apply the colors whenever the child views of the NIC
change. To model this better, we bind directly to the child views, as
opposed to the NIC; this keeps the colorization logic centralized.

Bug: 278765923
Flag: ACONFIG com.android.systemui.notifications_icon_container_refactor DEVELOPMENT
Test: atest SystemUITests
Test: manual - verify icon colors are correct on AOD

Change-Id: I4bd8fb7d181268065ecb976f5265f6ce657d086a