Refactored SFU recording path handling and fixed WebRTC screenshare recordings

labs/bbb-webrtc-sfu/lib/base/BaseProvider.js

labs/bbb-webrtc-sfu/lib/mcs-core/lib/media/MCSApiStub.js

.../bbb-webrtc-sfu/lib/mcs-core/lib/media/MediaController.js

...bbb-webrtc-sfu/lib/mcs-core/lib/model/RecordingSession.js

labs/bbb-webrtc-sfu/lib/mcs-core/lib/model/SfuUser.js

labs/bbb-webrtc-sfu/lib/screenshare/screenshare.js

labs/bbb-webrtc-sfu/lib/video/video.js