Update usages of refs for React 19 compatibility (#29536)

* Update usages of refs for React 19 compatibility

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

* Iterate

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

* Iterate

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

* Simplify

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

---------

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

test/unit-tests/components/structures/FilePanel-test.tsx

@@ -65,7 +65,9 @@ describe("FilePanel", () => {
                     roomId={room.roomId}
                     onClose={jest.fn()}
                     resizeNotifier={new ResizeNotifier()}
-                    ref={(ref) => (filePanel = ref)}
+                    ref={(ref) => {
+                        filePanel = ref;
+                    }}
                 />,
             );
             await screen.findByText("No files visible in this room");

test/unit-tests/components/structures/RoomView-test.tsx

@@ -128,7 +128,7 @@ describe("RoomView", () => {
         cleanup();
     });
 
-    const mountRoomView = async (ref?: RefObject<RoomView>): Promise<RenderResult> => {
+    const mountRoomView = async (ref?: RefObject<RoomView | null>): Promise<RenderResult> => {
         if (stores.roomViewStore.getRoomId() !== room.roomId) {
             const switchedRoom = new Promise<void>((resolve) => {
                 const subFn = () => {

test/unit-tests/components/structures/TimelinePanel-test.tsx

@@ -211,7 +211,9 @@ describe("TimelinePanel", () => {
                     timelineSet={timelineSet}
                     manageReadMarkers={true}
                     manageReadReceipts={true}
-                    ref={(ref) => (timelinePanel = ref)}
+                    ref={(ref) => {
+                        timelinePanel = ref;
+                    }}
                 />,
                 withClientContextRenderOptions(MatrixClientPeg.safeGet()),
             );