Pagure Issues can have a (list of) PRs 'linked' to them via the FIXES: XYZ comment in the PR.

This info is stored in the related_prs field within the issue:

"related_prs": [
            {
                "id": 261,
                "title": "Post discussion link to bz on propose"
            }
        ],

Make use of this data, to show Issues with "active" PRs in the Kanban board.

The two most basic usecases are "I'm waiting for a review" and "I need to act on the review". We can distinguish these states based on who is the assignee of the ticket, and the author of the last comment of the Pull Request.
* If these are the same the PR is "off my hands" and the ticket will be shown in a less dominant manner within the Assigned field (towards the bottom, greyed out)
* When different, the Issue's assignee should act. The ticket will be shown towards the top, and with some "look at me" color scheme/icon

This was proposed by @lruzicka - he sometimes misses the PR review, and is at the same time not happy to see "blocked" issues in a dominant position in the Assigned column.