Reinitialize completion list after switching room

(cherry picked from commit e15e10d319)

imports/NeoChat/Component/ChatBox/ChatBox.qml

@@ -227,6 +227,14 @@ Item {
         chatBar.inputFieldForceActiveFocusTriggered()
     }
 
+    Connections {
+        target: RoomManager
+
+        function onCurrentRoomChanged() {
+            chatBar.userAutocompleted = {};
+        }
+    }
+
     Connections {
         target: ChatBoxHelper