Change camera input live during call

[leona-ya]

Is your suggestion related to a problem? Please describe.
I'm always frustrated when I do a video call with element and want to change the camera input.

Describe the solution you'd like
Ability to change the camera during a call. An example solution would be during a call:

1. Change the camera in settings
2. Turn camera off and on again (maybe also doing that automatically when changing the camera in settings)
3. See the usage of the other camera

Describe alternatives you've considered
The only current possibility is to change the camera in the settings and restart the call.

Additional context
None

[jpggithub]

This kind of change is possible when you do a simple video call with Jitsi (aka out of a element call).

[SimonBrandner]

Closing in favour of #15595