Display new forum posts indicator on dashboard

THIS IS AN MUA PROJECT PROPOSAL THAT WILL BE OR HAS BEEN SUBMITTED FOR POSSIBLE MUA FUNDING. 

Overview

The old pre-3.5 dashboard used to have a "new forum posts" indicator - this was especially useful at our uni for teaching staff to be able to scan their courses and quickly see which need attention but i assume it was also also pretty useful for students. Teaching staff complained when it went anyway.

I think if possible it would be useful to extend this to include a notification for the course on the dashboard to display an icon with an indication of "new posts/entries" for a range of activities included in that course, but initially the forum is the key thing, and already has the "unread posts" functionality.

Tracker link: https://tracker.moodle.org/browse/MDL-58913

Summary

• Project size: small/medium
• Audience: primary schools, universities, work places
• Target users: teachers, students

User Stories 

As a teacher, I should be able to view an indicator to highlight the number of new forum posts for a course since my last visit.

As a student, I should be able to view an indicator to highlight the number of new forum posts for a course since my last visit.

Links to existing tracker issues, forum discussions, contrib plugins

https://tracker.moodle.org/browse/MDL-58913

https://tracker.moodle.org/browse/MDL-63051 says it was planned at some point for 3.6 work but got shelved.