Bind Webcam and WebRTC video stream to CallInterface

Add working mute and webcam on/off buttons.
Add rudimentary start webrtc call functionnality. This is only a first step, it will be improved in the future.

GitLab: #74
Change-Id: Ic3afde596a60fa2e9ea6199e3d632366078ec9fe
diff --git a/client/.env.development b/client/.env.development
index 6d453cd..503c414 100644
--- a/client/.env.development
+++ b/client/.env.development
@@ -1,2 +1,5 @@
 ESLINT_NO_DEV_ERRORS=true
-VITE_API_URL=http://localhost:5000
\ No newline at end of file
+VITE_API_URL=http://localhost:5000
+
+# This is the url to the temporary socket server in `jami-web/routes/fakeServerForWebRTC.js`
+VITE_SOCKET_URL=