Spike AXE A11Y testing in Cypress (#9111)

* Spike AXE A11Y testing in Cypress

* Fix NewRoomIntro breaking html/aria list rules

* Fix HeaderButtons breaking aria role semantics rules

* missing type

* Switch left panel from aside to nav and include space panel

* Give the page a main heading of the room name when viewing a room

* Use header landmark on RoomHeader

* Improve aria attributes on composer when autocomplete is closed

* Fix aria-owns on RoomHeader

* Give Spinner an aria role

* Give server picker help button an aria label

* Improve auth aria attributes and semantics

* Improve heading semantics in use case selection screen

* Fix autocomplete attribute to be valid

* Fix heading semantics on login page

* Improve Cypress axe testing

* Add axe tests

* Stop synapse after the timeline tests

* Await spinners to fade before percy snapshotting timeline tests

* Improve naming of plugin

* Update snapshots

* Fix accidental heading change

* Fix double synapse stoppage

* Fix Cypress timeline avatar assertions to be DPI agnostic

* Fix aria attributes on date separators

* delint

* Update snapshots

* Revert style change

* Skip redundant call

src/components/views/rooms/NewRoomIntro.tsx

@@ -219,8 +219,7 @@ const NewRoomIntro = () => {
         <span> { subText } { subButton } </span>
     );
 
-    return <div className="mx_NewRoomIntro">
-
+    return <li className="mx_NewRoomIntro">
         { !hasExpectedEncryptionSettings(cli, room) && (
             <EventTileBubble
                 className="mx_cryptoEvent mx_cryptoEvent_icon_warning"
@@ -230,7 +229,7 @@ const NewRoomIntro = () => {
         ) }
 
         { body }
-    </div>;
+    </li>;
 };
 
 export default NewRoomIntro;