Display Merge Request approval counts in Merge Request list

What does this MR do?

(CE Port https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/24500)

From !7611 (closed):

Add approval counts to Merge Request list.

See the 1 / 3 in the first Merge Request of the list:

https://gitlab.com/gitlab-org/gitlab-ee/uploads/d81aa04bb260ad192781918897a6f74b/image.png

No changes to the following page, note the current approvals:

https://gitlab.com/gitlab-org/gitlab-ee/uploads/317f981089a5e66d0c416c8d3ceb9440/image.png

Updated: Added some more styling.

https://gitlab.com/gitlab-org/gitlab-ee/uploads/f0447bee99239b1a4b72cc46d26d412d/image.png

Taking over to continue work since the original contributor doesn't have time.

What are the relevant issue numbers?

#1317 (closed)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated via this MR
• Tests added for this feature/bug
• Tested in all supported browsers
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Conforms to the database guides
• Link to e2e tests MR added if this MR has Requires e2e tests label. See the Test Planning Process.
• EE specific content should be in the top level /ee folder
• For a paid feature, have we considered GitLab.com plans, how it works for groups, and is there a design for promoting it to users who aren't on the correct plan?
• Security reports checked/validated by reviewer