Issue board - option to add column for tasks assigned to any user and tasks with a merge request

Description

I love the issue board feature, but for a team which are used to using the Milestone view of issues, moving to use issue boards isn't right for us.

Proposal

I suggest that issue boards could be enhanced by providing the option to add special columns:

• a column for tasks which are assigned to any user (maybe some would want to be able to target specific users, but that's not my use case)

This would enable the issue board to replicate the middle column of the Milestone view.

• I'd also suggest it would be good to have a column showing issues which currently have a Merge Request against them - in the Milestone view it can sometimes look like there's loads in progress, but when you check in detail they have all been 'done' and are waiting for the MR.

Longer term I could imagine the option to combine these with labels, so you could have a column showing issues with open MRs which have a label of 'front end' say, but that's beyond my use case and I appreciate would add far greater complexity to the UI.