RCFilters UI: Highlight behavior

RCFilters UI: Highlight behavior

Let there be highlight! and there were highlights
And RCFilters separated the highlight from the darkness
And it defined highlights as five colors
The lights are called yellow and green, and the darks red and blue
And there were colors and there were circles; one highlight.

This is the commit that adds highlight support for filters both in the backend
and the UI. The backend tags results based on which filter they fit and the
front end paints those results according to the color chosen by the user.
Highlights can be toggled off and on.

Also added circle indicators to the capsule items and each line of results
to indicate whether the line has more than one color affecting it.

Bug: T149467
Bug: T156164
Change-Id: I341c3f7c224271a18d455b9e5f5457ec43de802d