Continually recreating video.js instance on render is bad.
Instead, persist a single instance, and simply update the source and poster on the existing instance.
I'm a bit wary of adding props to this component due to the 'dispose' call, but I think 'source' and 'claim' will update together, so it shouldn't be an issue?
## Issue
5308: Ability to choose default play speed and theatre mode or regular playback size
## Comments
Initially, I used the local storage, as per 'muted' and 'volume' -- I thought that would be appropriate.
Later, I saw that Theater Mode is already using Client Settings, so I re-did everything to match that.
Also, there is an accompanying commit in lbyr-redux.
## Issue:
5119 "Video: Mobile UI + overlay for keyboard shortcut feedback" was disabled because the feature broke the chromecast button in Android Chrome
4913: Can't slide volume slider in pop out mode
I first tried to handle this at the floating player level, but it was impossible to hack there due to how 'react-draggable' works (it already moved the window before the "move" handler is called, so we can't do much).
Fix by overriding the dragging behavior of the videojs' VolumeBar class by not propagating the event further. It is odd that videojs didn't already do this, since it's SeekBar does stop the propagation.
## Issue
Fixes 4460 `unmuted state lost / reverted`
1. Play a video.
2. Press mute.
3. Drag the volume bar to unmute.
4. Play a new video --> the video starts muted.
## Fix
The `volumechange` handler was comparing against stale variables, so there are times where the state was not saved. Just save both `muted` and `volume` without additional gating (the gating is probably unnecessary in the first place, since we are in a onChange function).
Implementation:
- The code is placed in <VideoJs> instead of <VideoViewer> as we need to control the video itself. It's more self-contained here, rather than trying to pass refs around between parent and child.
- useState cannot be used as it will cause a re-render when the hint it clicked and dismissed. The DOM is used to hide the button.
