Display "mergeability" of Merge Request in the index

Description

The merge request list, for example /groups/<group-name>/merge-requests, is a fairly rudimentary list. Since this list is the most efficient way to see our team's testing work, I'd like to see additional information. This would allow us to address open merge requests more efficiently.

Merge Requests may have work outstanding or all work may be completed. We could display an icon indicating whether the MR is in a mergeable state in the index list

Proposal

Introduce an icon to the MR index list that easily distinguishes complete, mergeable MRs from those that are incomplete.

The icon would be displayed if (depending on the rules of the project):

• There are no merge conflicts
• There are no outstanding, unresolved discussions
• The associated pipeline has succeeded