The stream list left sidebar currently has 3 sections:
* Pinned (+ Muted pinned streams)
* Active (+ Muted active streams)
* Inactive streams
Previously, these sections were separated by horizontal lines, which
did not provide an easy way to discern why there were sections. We add
labels to these section dividers to help with this.
Additionally, within each section, we now sort all muted streams to
the bottom, so that they general minimal clutter.
Fixes#19812.
madrix01