Add low priority filter pill to the room list UI (#30060)

* Add low priority filter pill to the UI

* Fix tests

test/unit-tests/components/viewmodels/roomlist/RoomListViewModel-test.tsx

@@ -66,9 +66,17 @@ describe("RoomListViewModel", () => {
             mockAndCreateRooms();
             const { result: vm } = renderHook(() => useRoomListViewModel());
             // should have 6 filters
-            expect(vm.current.primaryFilters).toHaveLength(6);
+            expect(vm.current.primaryFilters).toHaveLength(7);
             // check the order
-            for (const [i, name] of ["Unreads", "People", "Rooms", "Mentions", "Invites", "Favourites"].entries()) {
+            for (const [i, name] of [
+                "Unreads",
+                "People",
+                "Rooms",
+                "Mentions",
+                "Invites",
+                "Favourites",
+                "Low priority",
+            ].entries()) {
                 expect(vm.current.primaryFilters[i].name).toEqual(name);
                 expect(vm.current.primaryFilters[i].active).toEqual(false);
             }

test/unit-tests/components/views/rooms/RoomListPanel/__snapshots__/RoomListPanel-test.tsx.snap

@@ -175,6 +175,19 @@ exports[`<RoomListPanel /> should not render the RoomListSearch component when U
           Favourites
         </button>
       </li>
+      <li
+        aria-selected="false"
+        role="option"
+      >
+        <button
+          aria-selected="false"
+          class="_chat-filter_5qdp0_8"
+          role="button"
+          tabindex="0"
+        >
+          Low priority
+        </button>
+      </li>
     </ul>
     <div
       class="mx_RoomListSkeleton"
@@ -424,6 +437,19 @@ exports[`<RoomListPanel /> should render the RoomListSearch component when UICom
           Favourites
         </button>
       </li>
+      <li
+        aria-selected="false"
+        role="option"
+      >
+        <button
+          aria-selected="false"
+          class="_chat-filter_5qdp0_8"
+          role="button"
+          tabindex="0"
+        >
+          Low priority
+        </button>
+      </li>
     </ul>
     <div
       class="mx_RoomListSkeleton"