New layout selector ui in user settings (#12676)

* feat: reworked the layout switcher

* feat: make the classname optional in EventTilePreview.tsx

* test: add tests to LayoutSwitcher

* feat: change appearance tab

* test: update appearance snapshot

* e2e: add tests

* css: add comment for gap overriding

src/components/views/elements/EventTilePreview.tsx

@@ -37,7 +37,7 @@ interface IProps {
     /**
      * classnames to apply to the wrapper of the preview
      */
-    className: string;
+    className?: string;
 
     /**
      * The ID of the displayed user