Display approval status on merge request listings
### Problem to solve
The problem is that it is difficult to see at a glance which requests have been approved and which are still waiting for review.
### Further details
Our team uses the merge requests view to see what merge requests are currently waiting to be reviewed. Often there are a large number of approved requests that are still waiting to be merged.
### Proposal
I currently see 2 possibilities for improving the usability here:
1. Display an icon / tag on the listing of each MR to show whether the MR is approved or not
2. Add a search filter for whether an MR is approved.
### What does success look like, and how can we measure that?
Success can be determined by the ability to quickly assess when which MRs require review and which do not.
### Links / references
issue