Jitsi widget: RoomVC: Show it in the banner when there is an active jitsi conference in a room.

Riot/Model/Room/RoomDataSource.h

@@ -17,6 +17,8 @@
 
 #import <MatrixKit/MatrixKit.h>
 
+#import "WidgetManager.h"
+
 /**
  The data source for `RoomViewController` in Vector.
  */
@@ -32,4 +34,11 @@
  */
 @property(nonatomic) BOOL markTimelineInitialEvent;
 
+/**
+ Check if there is an active jitsi widget in the room and return it.
+
+ @return a widget representating the active jitsi conference in the room. Else, nil.
+ */
+- (Widget *)jitsiWidget;
+
 @end