[mediacapture-main] enumerateDevices should only provide device info permission for granted device types (#645)

youennf has just created a new issue for https://github.com/w3c/mediacapture-main:

== enumerateDevices should only provide device info permission for granted device types ==
The spec allows to expose devices through enumerateDevices after a successful getUserMedia call.
It makes sense to restrict it to either device or device type.
Per-device would be good to have but might depend on the actual browser implementation.

Per device type seems like the minimum bar.
In particular, if a user agent is asking "Allow access to camera", it does not make real sense to leak microphones.

Please view or discuss this issue at https://github.com/w3c/mediacapture-main/issues/645 using your GitHub account