Rewrite <LoadMore /> as FC and TS (#25259)

app/javascript/mastodon/components/load_more.tsx

@@ -0,0 +1,24 @@
+import { FormattedMessage } from 'react-intl';
+
+interface Props {
+  onClick: (event: React.MouseEvent) => void;
+  disabled?: boolean;
+  visible?: boolean;
+}
+export const LoadMore: React.FC<Props> = ({
+  onClick,
+  disabled,
+  visible = true,
+}) => {
+  return (
+    <button
+      type='button'
+      className='load-more'
+      disabled={disabled || !visible}
+      style={{ visibility: visible ? 'visible' : 'hidden' }}
+      onClick={onClick}
+    >
+      <FormattedMessage id='status.load_more' defaultMessage='Load more' />
+    </button>
+  );
+};