PLT-3412 WebRTC Server side & System Console (#3706)

* WebRTC Server side

* WebRTC System Console

* Consistency on variable names

* Add turn and stun uri validation

config/config.json

@@ -220,5 +220,15 @@
         "Enable": false,
         "InterNodeListenAddress": ":8075",
         "InterNodeUrls": []
+    },
+    "WebrtcSettings": {
+        "Enable": false,
+        "GatewayWebsocketUrl": "",
+        "GatewayAdminUrl": "",
+        "GatewayAdminSecret": "",
+        "StunURI": "",
+        "TurnURI": "",
+        "TurnUsername": "",
+        "TurnSharedKey": ""
     }
 }