Track frequently used emojis in web UI (#5275)

* Track frequently used emojis in web UI

* Persist emoji usage, but debounce commits to the settings API

* Fix #5144 - Add tooltips to picker

* Display only 2 lines of frequently used emojis

app/javascript/mastodon/actions/settings.js

@@ -1,6 +1,8 @@
 import axios from 'axios';
+import { debounce } from 'lodash';
 
 export const SETTING_CHANGE = 'SETTING_CHANGE';
+export const SETTING_SAVE   = 'SETTING_SAVE';
 
 export function changeSetting(key, value) {
   return dispatch => {
@@ -14,10 +16,16 @@ export function changeSetting(key, value) {
   };
 };
 
+const debouncedSave = debounce((dispatch, getState) => {
+  if (getState().getIn(['settings', 'saved'])) {
+    return;
+  }
+
+  const data = getState().get('settings').filter((_, key) => key !== 'saved').toJS();
+
+  axios.put('/api/web/settings', { data }).then(() => dispatch({ type: SETTING_SAVE }));
+}, 5000, { trailing: true });
+
 export function saveSettings() {
-  return (_, getState) => {
-    axios.put('/api/web/settings', {
-      data: getState().get('settings').toJS(),
-    });
-  };
+  return (dispatch, getState) => debouncedSave(dispatch, getState);
 };