Add jump to date functionality to date headers in timeline v2 (#7339)

Fix https://github.com/vector-im/element-web/issues/7677

Utilizes MSC3030: https://github.com/matrix-org/matrix-doc/pull/3030

https://user-images.githubusercontent.com/558581/150060664-79627573-f4fd-497c-b726-dc3485854bd0.png

src/hooks/useCombinedRefs.ts

@@ -0,0 +1,38 @@
+/*
+Copyright 2022 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+import { useRef, useEffect } from 'react';
+
+// Takes in multiple React refs and combines them to reference the same target/element
+//
+// via https://itnext.io/reusing-the-ref-from-forwardref-with-react-hooks-4ce9df693dd
+export const useCombinedRefs = (...refs) => {
+    const targetRef = useRef();
+
+    useEffect(() => {
+        refs.forEach(ref => {
+            if (!ref) return;
+
+            if (typeof ref === 'function') {
+                ref(targetRef.current);
+            } else {
+                ref.current = targetRef.current;
+            }
+        });
+    }, [refs]);
+
+    return targetRef;
+};