Color Picker Fragment UX Polish

Adjustments to the header, bottom sheet tabs, subheader and color
options to make sure they align with the most updated UX requirements.
Also made sure common ItemSpacing is used.

Before: https://screenshot.googleplex.com/8ZdxAhznKfP6K8z.png
After: https://screenshot.googleplex.com/5CRw2g3abxpTQv8.png

Bug: 269450711
Test: Manually verified new UI, made sure existing color picker unit
tests still pass.

Change-Id: Idb06ca5e7bf8b59ab21b34ffe1dbfb508f7a39e6