Update ReactiveCache call sites to use async/await for Meteor 3.0

Part 3 of ReactiveCache async migration:
- Add await before all ReactiveCache.getX() calls
- Make functions containing ReactiveCache calls async
- Convert forEach/map/filter loops with async callbacks to for...of
- Update model helpers, Meteor methods, JsonRoutes handlers
- Update collection hooks (.before/.after insert/update/remove)
- Update .allow() callbacks to async

Files updated across models/ and server/ directories:
- Model files: cards, boards, lists, swimlanes, activities, users,
  checklists, checklistItems, customFields, attachments, integrations,
  cardComments, settings files, creators, exporters, and more
- Server files: publications, methods, notifications, routes, migrations

server/lib/emailLocalization.js

@@ -17,13 +17,13 @@ EmailLocalization = {
    * @param {String} options.language - Language code to use (if not provided, will try to detect)
    * @param {String} options.userId - User ID to determine language (if not provided with language)
    */
-  sendEmail(options) {
+  async sendEmail(options) {
     // Determine the language to use
     let lang = options.language;
 
     // If no language is specified but we have a userId, try to get the user's language
     if (!lang && options.userId) {
-      const user = ReactiveCache.getUser(options.userId);
+      const user = await ReactiveCache.getUser(options.userId);
       if (user) {
         lang = user.getLanguage();
       }