Move user deletion to worker (#15586)

* WIP(delete): remove business logic from controller

* fix(deletion): handle group leave logic on app server still

* fix(lint): unused import

* fix(import): bracket syntax

* fix(test): adapt test for worker flow

* fix(deletion): update delete/feedback form copy

* fix(text): don't break to new paragraph about Gems

* fix(deletion): remove orphaned chat messages

* Revert "fix(deletion): handle group leave logic on app server still"

This reverts commit 9db541f4c3.

* fix(tests): remove tests
These can potentially be tested in the worker's suite? They target functionality that the group leave route handles within the deletion flow

* fix(lint): no-undef

* refactor redis setup into own file and use ioredis

* use bullmq directly to schedule jobs

* add space

* add key prefix

* add semicolon

* fix(jobs): update redis package

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Co-authored-by: Phillip Thelen <phillip@habitica.com>

website/server/models/group.js

@@ -1457,6 +1457,7 @@ schema.methods.leave = async function leaveGroup (user, keep = 'keep-all', keepC
 
     if (members.length === 0) {
       promises.push(group.deleteOne());
+      promises.push(Chat.deleteMany({ groupId: group._id }));
       return Promise.all(promises);
     }
   }