Enable "jsx-a11y/alt-text" and "jsx-a11y/label-has-associated-control" lint rules (#10361)

* enable "jsx-a11y/alt-text" lint rule

* enable "jsx-a11y/label-has-associated-control"

src/components/views/rooms/MessageComposer.tsx

@@ -538,6 +538,8 @@ export class MessageComposer extends React.Component<IProps, IState> {
                 <div className="mx_MessageComposer_replaced_wrapper" key="room_replaced">
                     <div className="mx_MessageComposer_replaced_valign">
                         <img
+                            aria-hidden
+                            alt=""
                             className="mx_MessageComposer_roomReplaced_icon"
                             src={require("../../../../res/img/room_replaced.svg").default}
                         />