Simple structuring of the room list itself

This covers the larger parts of the design, but doesn't deal with the nuances of hover states, badge sizing, etc.

src/stores/room-list/ListLayout.ts

@@ -14,7 +14,7 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-const TILE_HEIGHT_PX = 34;
+const TILE_HEIGHT_PX = 44;
 
 interface ISerializedListLayout {
     numTiles: number;