Separate useDevices to full + light version #15991
Description
useDevices is being used by the local media buttons.
The devices mixin, which the useDevices composable comes from, was meant to be used only in the settings and media devices dialogs. It handled devices in a completly separate way from the devices used in the call (except for the fact that, due to historical reasons for browser compatibility, only a single device of each kind could be active at the same time, so changing the device in the dialog also changed it indirectly in the call through the MediaDevicesManager). Due to that, it requests its own audio and video streams and has its own virtual background handler to be able to show the previews.
When the composable started to be used in the local media buttons it started to request those streams when the buttons were mounted, and then it never freed them.
Although the streams are now freed they should not be requested in first place, because they are never used (and neither the virtual background) and it is just duplicating the streams used in the call.
Originally posted by @danxuliu in #15989 (review)