Various ARIA a11y fixes.

Notate RightPanel tabs.
Shorten Screen Reader queues.
Make AccessibleTooltipButton screen reader friendly
Flatten DOM for Sticker button using React Fragments

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

src/components/views/rooms/Stickerpicker.js

@@ -409,9 +409,9 @@ export default class Stickerpicker extends React.Component {
                 >
                 </AccessibleButton>;
         }
-        return <div>
+        return <React.Fragment>
             {stickersButton}
             {this.state.showStickers && stickerPicker}
-        </div>;
+        </React.Fragment>;
     }
 }