This commit updates the plugin to follow the latest guidelines, as
shown in discourse-plugin-skeleton, removing the explicit require calls
and using config/routes.rb for defining all routes.
This change makes it possible to associate an assign notification with the `assignments` record that creates the notification. It'll be needed for the assignments tab in the new experimental user menu, see https://github.com/discourse/discourse/pull/17379.
Change `topic_id` to polymorphic approach (In the next step we will allow assigning to individual post)
`topic_id` column is still used for efficient display of assigned users on topic list (to avoid scanning posts)
Ability to assign groups.
To assign group, user must have a right to send a message to that group.
In addition, 2 jobs were introduced, - AssignNotification and UnassignNotification to inform interested users in the background about the new assignment.
Penar Musaraj
Bianca Nenciu
Osama Sayegh
Rafael dos Santos Silva
Natalie Tay
Krzysztof Kotlarek
Jarek Radosz