[Glitch] Refactor privacyPrefence() to use priority list

Port f2d9a3c239 to glitch-soc

app/javascript/flavours/glitch/reducers/compose.js

@@ -207,15 +207,8 @@ const insertEmoji = (state, position, emojiData) => {
 };
 
 const privacyPreference = (a, b) => {
-  if (a === 'direct' || b === 'direct') {
-    return 'direct';
-  } else if (a === 'private' || b === 'private') {
-    return 'private';
-  } else if (a === 'unlisted' || b === 'unlisted') {
-    return 'unlisted';
-  } else {
-    return 'public';
-  }
+  const order = ['public', 'unlisted', 'private', 'direct'];
+  return order[Math.max(order.indexOf(a), order.indexOf(b), 0)];
 };
 
 const hydrate = (state, hydratedState) => {