Upgrade to mongoose 7 (#14971)

* remove some unused dependencies

* update mongoose version

* make common tests pass

* Make unit tests pass

* make api v3 integration tests pass

* fix lint issues

* fix issue with package-lock

* fix(lint): we don't need no .js

* fix(lint): update to latest config-habitrpg

* chore(npm): update package locks

* fix(test): replace deprecated fn

* chore(package): update eslint-habitrpg again

* fix(lint): server linting

* fix(lint): client linting

* fix(client): correct mangled common imports

* chore(npm): update package-locks

* fix(lint): punctuation, module

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Co-authored-by: SabreCat <sabrecat@gmail.com>
Co-authored-by: SabreCat <sabe@habitica.com>

test/api/v3/integration/challenges/DELETE-challenges_challengeId.test.js

@@ -87,7 +87,7 @@ describe('DELETE /challenges/:challengeId', () => {
       const testTask = _.find(tasks, task => task.text === taskText);
 
       expect(testTask.challenge.broken).to.eql('CHALLENGE_DELETED');
-      expect(testTask.challenge.winner).to.be.null;
+      expect(testTask.challenge.winner).to.be.undefined;
     });
   });
 });