Add background blur feature for supported devices

[toger5]

This adds background blur via @livekit/track-processors for supported browsers.
The option can be found in the video tab of the settings.

The fallback will be a greyed out checkbox (on firefox for instance)
This way firefox users get informed why it does not work on their side if other users tell them where to set it up.

Sadly this is not exactly done the way we would want to set it up see: livekit/track-processors-js#50

[toger5]

how do we deal with lk modules that dont fullfill the ts lints?

[toger5]

how do we deal with lk modules that dont fullfill the ts lints?

I found what we needed:
@types/dom-mediacapture-transform

[hughns]

I've suggested some cleanup. Furthermore I think you could deduplicate some of the code into something like a useBlur() or canBlur(). This might make adding tests easier too.

[toger5]

Furthermore I think you could deduplicate some of the code into something like a useBlur() or canBlur(). This might make adding tests easier too.

I think @robintown has an idea how we might be able to reuse the track from the lobby to the in call view. Than this might come for free.

But in this pr we should at least get rid of the duplicated let blur = useMemo sections

[hughns]

Suggested change

	"blur_not_supported_by_browser": "(Background blur is not supported by this browser)",
	"blur_not_supported_by_browser": "(Background blur is not supported by this device)",

...because this message also appears when EC is embedded as widget and the user isn't aware that it is a browser.

[hughns]

Currently this PR causes some (large) assets to be loaded from jsdelivr.net and googleapis.com at runtime: