Ensure interface gradually reduces visible buttons when viewport shrinks (#33477)

* Rewrite Measured to be a functional component

* Add tests to cover narrow viewports

* lint

* breakpoint is optional

* Cleanup

* Provide default value

* Fixup

* fix two snaps

* Update screenshot

* and the other one

* unfake CIDER

* Update snaps AGAIN

apps/web/src/components/structures/ThreadView.tsx

@@ -435,7 +435,7 @@ export default class ThreadView extends React.Component<IProps, IState> {
                             PosthogTrackers.trackInteraction("WebThreadViewBackButton", ev);
                         }}
                     >
-                        <Measured sensor={this.card} onMeasurement={this.onMeasurement} />
+                        <Measured breakpoint={400} sensor={this.card} onMeasurement={this.onMeasurement} />
                         <div className="mx_ThreadView_timelinePanelWrapper">{timeline}</div>
 
                         {ContentMessages.sharedInstance().getCurrentUploads(threadRelation).length > 0 && (