RoomListStore: Support specific sorting requirements for muted rooms (#29665)

* Sort muted rooms to the bottom of the room list

* Re-insert room on mute/unmute

* Write tests

* Fix broken playwright test

Muted rooms are at the bottom, so we need to scroll.

playwright/e2e/left-panel/room-list-panel/room-list.spec.ts

@@ -108,6 +108,11 @@ test.describe("Room list", () => {
             // Remove hover on the room list item
             await roomListView.hover();
 
+            // Scroll to the bottom of the list
+            await page.getByRole("grid", { name: "Room list" }).evaluate((e) => {
+                e.scrollTop = e.scrollHeight;
+            });
+
             // The room decoration should have the muted icon
             await expect(roomItem.getByTestId("notification-decoration")).toBeVisible();