feat(ReceiveVideoController): Add the ability to send constraints in the new format.

Add the ability to send the bridge messages for the receiver video constraints in the new format directly.

JitsiConference.js

     return this.speakerStatsCollector.getStats();
 };
 
+/**
+ * Sets the constraints for the video that is requested from the bridge.
+ *
+ * @param {Object} videoConstraints The constraints which are specified in the
+ * following format. The message updates the fields that are present and leaves the
+ * rest unchanged on the bridge. Therefore, any field that is not applicable anymore
+ * should be cleared by passing an empty object or list (whatever is applicable).
+ * {
+ *      'lastN': 20,
+ *      'selectedEndpoints': ['A', 'B', 'C'],
+ *      'onStageEndpoints': ['A'],
+ *      'defaultConstraints': { 'maxHeight': 180 },
+ *      'constraints': {
+ *          'A': { 'maxHeight': 720 }
+ *      }
+ * }
+ */
+JitsiConference.prototype.setReceiverConstraints = function(videoConstraints) {
+    this.receiveVideoController.setReceiverConstraints(videoConstraints);
+};
+
 /**
  * Sets the maximum video size the local participant should receive from remote
  * participants.

modules/qualitycontrol/ReceiveVideoController.js

 import { getLogger } from 'jitsi-meet-logger';
+import isEqual from 'lodash.isequal';
 
 import * as JitsiConferenceEvents from '../../JitsiConferenceEvents';
 
         return changed;
     }
 
+    /**
+     * Updates the receiver constraints sent to the bridge.
+     *
+     * @param {Object} videoConstraints
+     * @returns {boolean} Returns true if the the value has been updated, false otherwise.
+     */
+    updateReceiverVideoConstraints(videoConstraints) {
+        const changed = !isEqual(this._receiverVideoConstraints, videoConstraints);
+
+        if (changed) {
+            this._receiverVideoConstraints = videoConstraints;
+            logger.debug(`Updating ReceiverVideoConstraints ${JSON.stringify(videoConstraints)}`);
+        }
+
+        return changed;
+    }
+
     /**
      * Updates the list of selected endpoints.
      *
             }
         }
     }
+
+    /**
+     * Sets the receiver constraints for the conference.
+     *
+     * @param {Object} constraints The video constraints.
+     */
+    setReceiverConstraints(constraints) {
+        if (!this._receiverVideoConstraints) {
+            this._receiverVideoConstraints = new ReceiverVideoConstraints();
+        }
+
+        const constraintsChanged = this._receiverVideoConstraints.updateReceiverVideoConstraints(constraints);
+
+        constraintsChanged && this._rtc.setNewReceiverVideoConstraints(constraints);
+    }
 }