Unread Sorting - Add option for sorting in OptionsMenuView (#31754)

* Add new sort option

* Support new sorting algorithm in vm

* Add option item for unread sorter

* Add tests

test/viewmodels/room-list/RoomListHeaderViewModel-test.ts

@@ -271,6 +271,7 @@ describe("RoomListHeaderViewModel", () => {
         it.each([
             ["recent" as const, SortingAlgorithm.Recency],
             ["alphabetical" as const, SortingAlgorithm.Alphabetic],
+            ["unread-first" as const, SortingAlgorithm.Unread],
         ])("should resort when sort is called with '%s'", (option, expectedAlgorithm) => {
             const resortSpy = jest.spyOn(RoomListStoreV3.instance, "resort").mockImplementation(jest.fn());
             vm = new RoomListHeaderViewModel({ matrixClient, spaceStore: SpaceStore.instance });