There were regressions in the form of JS errors in Filmstrip introduced
when the call/ring overlay was rewritten in React.

Rewrite the non-React RingOverlay into the React Component CallOverlay
in a way which makes it easier to port to React Native.

* fix(vertical-filmstrip): different label animations for filmstrip states

Instead of one timing for sliding the video status label left and right,
have different timings depending on the filmstrip state. To facilitate
triggering the different animations, add more classes to the labels
that need to move that specify the filmstrip state.

- Faster transition if focusing on self-view with videos present so
  the label does not overlap videos transitioning from 0 opacity.
- Transition delay when de-focusing on self-view with videos present
  so videos have time to go away before the label moves over them.
- Maintain no movement if there are no videos, regardless of
  filmstrip toggle state.
- Different delays for when the filmstrip is being toggled visible
  and hidden if there are remote videos visible.

* SQUASH: remove remote videos count

* SQUASH: add docs to scss

The video status labels, which include recording and hd status,
have been moved back to the top left while in vertical filmstrip
mode. The following had to be done:
- Remove styling to move the labels to the bottom left
- For VideoStatusLabel, move filmstrip remote video count, toggle
  state, and 1:1 state into redux.
- Use middleware to emit out to the Recording label when the
  filmstrip changes.
- Create an empty Filmstrip file for web and identify the existing
  Filmstrip component as native.