FEATURE - Moderators can create and manage groups (#10432)

Enabling the moderators_manage_categories_and_groups site setting will allow moderator users to create/manage groups.

* show New Group form to moderators

* Allow moderators to update groups and read logs, where appropriate

* Rename site setting from create -> manage

* improved tests

* Migration should rename old log entries

* Log group changes, even if those changes mean you can no longer see the group

* Slight reshuffle

* RouteTo /g if they no longer have permissions to view group

test/javascripts/models/user-test.js

@@ -52,6 +52,7 @@ QUnit.test("canMangeGroup", assert => {
   );
 
   group.set("automatic", false);
+  group.setProperties({ can_admin_group: true });
 
   assert.equal(
     user.canManageGroup(group),