Guild A/B test and Achievement (#8740)

* WIP(guilds): AB test pester modal

* WIP(AB-test): guild pester cont'd

* fix(style): linting error

* fix(AB-test): markModified and notif enum

* fix(tests): update AB expectations

* fix(modal): remove extra includes

* feat(achievements): add Joined Guild cheevo
Also removes unused achievement sprites, and properly saves counter used in A/B testing

* fix(style): linting error from conflict

test/api/v3/integration/groups/POST-groups.test.js

@@ -74,6 +74,18 @@ describe('POST /group', () => {
       expect(updatedUser.guilds).to.include(guild._id);
     });
 
+    it('awards the Joined Guild achievement', async () => {
+      await user.post('/groups', {
+        name: 'some guild',
+        type: 'guild',
+        privacy: 'public',
+      });
+
+      let updatedUser = await user.get('/user');
+
+      expect(updatedUser.achievements.joinedGuild).to.eql(true);
+    });
+
     context('public guild', () => {
       it('creates a group', async () => {
         let groupName = 'Test Public Guild';