Remove hardcoded color for cellular data usage view

1. Remove hardcoded color and create colorStateList instead
2. Remove warning color and use attr textColorError instead
3. Add function to extract color from colorStateList

Bug: 32592245
Test: manual - Take screenshots
Change-Id: I7f0a54b304b09b99ba1f255952e7e99e009a4d2a
6 files changed