Ability to pop out video tiles ("picture-in-picture")

[SimonBrandner]

One request that we've been getting recently is a way to activate the browser's picture-in-picture functionality from within Element Call.

Yet to be discovered:

• What are the use cases for this?
• Would we rather provide a feature that lets you pop out a specific tile only, or one that creates a window always highlighting the active speaker?
• On the implementation side: how does this interact with LiveKit automatically unsubscribing from video streams that are off screen?
• Is this worth implementing given that Firefox doesn't yet support the relevant APIs?
• Design (potential for integrating it with the drag-and-drop interaction, such that you could literally drag a tile and drop it outside the window to pop it out, much like a browser tab? or do we need something less surprising like a button)

[robintown]

I've elaborated on this ticket based on what I believe the title was referring to

[bblacher]

I'd love to have the ability to pop out specific screen shares. This would mean that one can watch two screen shares at the same time. (This ability should be in element desktop as well) I think discord does a great job at this.