ref(stats): start the statsEmitter for both mobile and web

Moves the statsEmitter.start() invocation to the middleware of
the connection-indicator feature, so that it's started for both mobile
and web (now mobile needs RTP stats for the tests).

conference.js

     getLocationContextRoot,
     getJitsiMeetGlobalNS
 } from './react/features/base/util';
-import { statsEmitter } from './react/features/connection-indicator';
 import { showDesktopPicker } from './react/features/desktop-picker';
 import { appendSuffix } from './react/features/display-name';
 import {
             }
         });
 
-        statsEmitter.startListeningForStats(room);
-
         room.addCommandListener(this.commands.defaults.ETHERPAD,
             ({ value }) => {
                 APP.UI.initEtherpad(value);

react/features/connection-indicator/index.js

 export * from './components';
 
 export { default as statsEmitter } from './statsEmitter';
+
+import './middleware';

react/features/connection-indicator/middleware.js

+// @flow
+
+import { MiddlewareRegistry } from '../base/redux';
+import { CONFERENCE_JOINED } from '../base/conference';
+
+import { statsEmitter } from './index';
+
+/**
+ * Implements the middleware of the feature connection-indicator.
+ *
+ * @param {Store} store - The redux store.
+ * @returns {Function}
+ */
+// eslint-disable-next-line no-unused-vars
+MiddlewareRegistry.register(store => next => action => {
+    switch (action.type) {
+    case CONFERENCE_JOINED: {
+        statsEmitter.startListeningForStats(action.conference);
+        break;
+    }
+    }
+
+    return next(action);
+});
+