Rework the roadmap page based on Mark Reynold's work
    
    - Make the tags list display in the same way as in the issue list page
    - Add the milestones using the `target` icon
    - Add all the status Open|Closed|All as we do in the issue list page
    - Fix the logic to properly display the Closed issues
    - Remove some of the redundant variables
    - Simplify some small bits of code