- log upload captions params

It now attempts to convert the uploaded caption file to WebVTT and
updates the index file.

Some additional validation/normalization is added for the language tag,
and some cleanup has been done for logging.

Makes testing easier

FFmpeg has pretty good format autodetection even if the filename has the
'.txt' extension, so just rely on that. It'll even pull subtitles out of
video files - although I expect we'll have size limits so that doesn't
happen.

Rather than running the tool in a loop, I'm using inotify to watch for
new files being created (ideally, the other rap workers will be migrated
to this style in the future). The trigger for processing is the creation
of the .json index file for the uploaded track.

 - track FS caller using UUID so we can find when the channel was cre…

   This will help us hunt an issue where a channel gets stuck in a voice conference.

Make whiteboard toolbar accessible via keyboard

Fix presentation upload drop zone showing red

Add some logs to the external video sync

 - resign screenshare jars with cert expiring on may 28, 2021

Handle incorrect presentationId passed from client

Closed captions prototype

Linting and other minor changes to closed captions pr

Stop obsolete toasts for published polls

Fix breakout showing wrong message in breakout start