Preparatory Work for Smaller user doc (WIP) (#10245)

* protect all paths in user.pre(save using this.isDirectSelected to see if a field is available

* fix linting

* authWithHeaders: specify user fields to exclude instead of the ones to include, add comments, doc and improve test

* add more options to unit helper generateReq and add tests for excluding fields in authWithHeaders

website/server/controllers/api-v3/user.js

@@ -55,6 +55,11 @@ let api = {};
  * Tags
  * TasksOrder (list of all ids for dailys, habits, rewards and todos)
  *
+ * @apiParam (Query) {UUID} userFields A list of comma separated user fields to be returned instead of the entire document. Notifications are always returned.
+ *
+ * @apiExample {curl} Example use:
+ * curl -i https://habitica.com/api/v3/user?userFields=achievements,items.mounts
+ *
  * @apiSuccess {Object} data The user object
  *
  * @apiSuccessExample {json} Result: