Force refresh threads timeline

Fixes vector-im/element-web#18947

In the absence of a proper pending events / remote echo setup it seems fairly difficult to get the timeline to update

Adding a temporary helper to force refresh the timeline and not swallow local events when sending a message from the thread sidebar

src/components/structures/TimelinePanel.tsx

@@ -1179,6 +1179,12 @@ class TimelinePanel extends React.Component<IProps, IState> {
         this.setState(this.getEvents());
     }
 
+    // Force refresh the timeline before threads support pending events
+    public refreshTimeline(): void {
+        this.loadTimeline();
+        this.reloadEvents();
+    }
+
     // get the list of events from the timeline window and the pending event list
     private getEvents(): Pick<IState, "events" | "liveEvents" | "firstVisibleEventIndex"> {
         const events: MatrixEvent[] = this.timelineWindow.getEvents();