[Glitch] Expose enabled features to the frontend

Port 94bceb8683e1993842bdb0344c8c70c6fdabc652 to glitch-soc

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

app/javascript/flavours/glitch/initial_state.js

@@ -1,6 +1,5 @@
 // @ts-check
 
-
 /**
  * @typedef {[code: string, name: string, localName: string]} InitialStateLanguage
  */
@@ -72,6 +71,7 @@
  * @property {object} local_settings
  * @property {number} max_feed_hashtags
  * @property {number} poll_limits
+ * @property {string[]} features
  */
 
 const element = document.getElementById('initial-state');
@@ -166,4 +166,12 @@ export function getAccessToken() {
   return getMeta('access_token');
 }
 
+/**
+ * @param {string} feature
+ * @returns {boolean}
+ */
+export function isFeatureEnabled(feature) {
+  return initialState?.features?.includes(feature) || false;
+}
+
 export default initialState;