Feeds the current track (if any), and therefore device it's using
into the device selection dropdown and implement a some somewhat
complex logic to observe when the 'default' device has changed to
a different actual devbice between when we opened it and now, and
display the device we're actually using as selected instead.

The comments should explain more, including the caveat that we can't
do the same detective work if the device is one of several devices
on the same bit of hardware. This is because is uses the same groupId
comparison technique used by Livekit in `normalizeDeviceId` to do
a smiliar thing.

Co-authored-by: Timo <[email protected]>

(and... add comments)

…im/element-call into dbkr/show_device_actually_in_use