[Glitch] Change design of edit media modal in web UI

Port 11786f1114 to glitch-soc

Signed-off-by: Claire <claire.github-309c@sitedethib.com>

app/javascript/flavours/glitch/features/compose/components/character_counter.tsx

@@ -0,0 +1,16 @@
+import { length } from 'stringz';
+
+export const CharacterCounter: React.FC<{
+  text: string;
+  max: number;
+}> = ({ text, max }) => {
+  const diff = max - length(text);
+
+  if (diff < 0) {
+    return (
+      <span className='character-counter character-counter--over'>{diff}</span>
+    );
+  }
+
+  return <span className='character-counter'>{diff}</span>;
+};