* fix regression from llhls when merging playlists
* set 2 second Group Of Pictures (GOP) size
* Rewrite HLS playlist to remove partial segments
* Add debouncing GenServer for manifest uploading
Fixes race condition by disallowing parallel manifest uploads.
This will also remove the many unneeded manifest updates sent to
Tigris before stream has finished.
* handle multitrack in Admin.merge_videos
* fix clipper for multitrack
* Create thumbnails module
* Implement multiple thumbnails
* Stop processing thumbnails after the last marker is created
* Create video_thumbnails table
* Store video thumbnails in db
* Avoid crashing the pipeline on thumbnail inserts with on_conflict: :nothing
* Only update the first thumbnail. Let use select the rest
Membrane is sending `track_playable` when the first part is ready, not
when the first full segment. This seems to cause Vidstack to stall when
the 'just went live' popup is clicked too quiclky.
This change simply waits @segment_duration seconds before toggling live
Allows using /live + <stream_key> or /<stream-key> or /<stream-key> +
<stream_key>, but no other combination
Moves all post-connection logic out of the Validator and into the
Pipeline
Delays calling init_livestream! until the stream is validated
Removes video_id from Validator config
Delays attaching HLS output until the stream is validated
User interface for stream key
