Drag challenge tasks (#12204)

* Allow challenge tasks to be draggable by leaders and admins

* Drag challenge tasks, ensure they're ordered

* Ensure group tasks are ordered properly, make draggable

* Add tests, fix broken tests

* Resolve merge conflict

* Remove console.log()

* Address code review comments

* Code review fixes

* Fix lint

* Fix importing

* taskManager

* Lint

* Fix collapseChecklist test

Co-authored-by: Sabe Jones <sabrecat@gmail.com>

test/api/v3/integration/tasks/POST-tasks_unlink-all_challengeId.test.js

@@ -97,7 +97,7 @@ describe('POST /tasks/unlink-all/:challengeId', () => {
     await user.del(`/challenges/${challenge._id}`);
     await user.post(`/tasks/unlink-all/${challenge._id}?keep=keep-all`);
     // Get the task for the second user
-    const [, anotherUserTask] = await anotherUser.get('/tasks/user');
+    const [anotherUserTask] = await anotherUser.get('/tasks/user');
     // Expect the second user to still have the task, but unlinked
     expect(anotherUserTask.challenge).to.eql({
       taskId: daily._id,