Add face pile to rooms (#11356)

* Add face pile to rooms

* Migrate FacePile to use Compound

* Fix CI

* Use FacePile component in room header

* Add facepile tests

* Make dead code CI happy

* Lint

* Fix tests

* Fix CSS selectors

* Update room face pile snapshot

* Use useMemo instead of useState and useEffect

* Remove unused imports

* Update snapshot

* Update snapshot

test/components/views/elements/RoomFacePile-test.tsx

@@ -0,0 +1,38 @@
+/*
+Copyright 2023 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 { render } from "@testing-library/react";
+import React from "react";
+
+import { mkRoom, mkRoomMember, stubClient, withClientContextRenderOptions } from "../../../test-utils";
+import RoomFacePile from "../../../../src/components/views/elements/RoomFacePile";
+import DMRoomMap from "../../../../src/utils/DMRoomMap";
+import { MatrixClientPeg } from "../../../../src/MatrixClientPeg";
+
+describe("<RoomFacePile />", () => {
+    it("renders", () => {
+        const cli = stubClient();
+        DMRoomMap.makeShared(cli);
+        const room = mkRoom(cli, "!123");
+
+        jest.spyOn(room, "getJoinedMembers").mockReturnValue([mkRoomMember(room.roomId, "@bob:example.org", "join")]);
+
+        const { asFragment } = render(
+            <RoomFacePile onlyKnownUsers={false} room={room} />,
+            withClientContextRenderOptions(MatrixClientPeg.get()!),
+        );
+
+        expect(asFragment()).toMatchSnapshot();
+    });
+});