RecordRTC: Add ability to choose camera & microphone

Currently, RecordRTC does not allow a choice of camera or microphone, even ignoring system defaults. Since WebRTC supports media device querying and selection (see demo at https://webrtc.github.io/samples/src/content/devices/input-output/), a great improvement to RecordRTC functionality in Moodle would be the ability to choose camera & microphone.

STEPS:

Open a page with an Atto editor.

Click either "Record audio" or "Record video" button.

Click "Start recording" button

Recording starts using laptop camera and microphone.

WHAT I EXPECT/DESIRE:

The ability to control which camera and microphone is recorded.