[Videos] Video player - PR #2 - better web support (#4732)

* attempt some sort of "usurping" system

* polling-based active video approach

* split into inner component again

* click to steal active video

* disable findAndActivateVideo on native

* new intersectionobserver approach - wip

* fix types

* disable perf optimisation to allow overflow

* make active player indicator subtler, clean up video utils

* partially fix double-playing

* start working on controls

* fullscreen API

* get buttons working somewhat

* rm source from where it shouldn't be

* use video elem as source of truth

* fix keyboard nav + mute state

* new icons, add fullscreen + time + fix play

* unmount when far offscreen + round 2dp

* listen globally to clicks rather than blur event

* move controls to new file

* reduce quality when not active

* add hover state to buttons

* stop propagation of videoplayer click

* move around autoplay effects

* increase background contrast

* add subtitles button

* add stopPropagation to root of video player

* clean up VideoWebControls

* fix chrome

* change quality based on focused state

* use autoLevelCapping instead of nextLevel

* get subtitle track from stream

* always use hlsjs

* rework hls into a ref

* render player earlier, allowing preload

* add error boundary

* clean up component structure and organisation

* rework fullscreen API

* disable fullscreen on iPhone

* don't play when ready on pause

* debounce buffering

* simplify giant list of event listeners

* update pref

* reduce prop drilling

* minimise rerenders in `ActiveViewContext`

* restore prop drilling

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Co-authored-by: Samuel Newman <10959775+mozzius@users.noreply.github.com>
Co-authored-by: Hailey <me@haileyok.com>

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