Use framework style for section headers and visual tweaks

- Use list separator style from framework for the blue headers
in our app (frequent header, recent header, kind type headers)
--> this allows us to get reduce the number of views in our
view tree because the divider is now an asset and part of the
TextView background.

- Adjust padding so it lines up with the new headers now

- Minor visual tweaks

Bug: 5136189
Change-Id: I7b10cc7e608b809d1a97ad8d8c59e31ab9d77e11