Ability to see and sort on vote count from Issues and MR lists

This should be done after #3672 (closed).

We had this previously for MRs. In this case, it would be great to have a +34 / -23 in the list view, so one can quickly see things that are very popular.

The ability to sort for this is vital for the usage of this feature.

Discussed with @dzaporozhets in a call:

Issue with +1, -1

If you have a single count of things that are +1 or -1, this doesn't give a good idea of how popular / interesting an issue is. An issue with +100 and -100 is more interesting than one with +1 and -1, therefore a single count is misleading.

This requires this:

Proposal: show 👍 & 👎 by default and make available in API

We show the 👍 and 👎 icons by default, this will prompt people to click these more. These are used specifically for voting.

Additionally, we make these available in the API, for instances as upvotes: 34, downvotes: 23, so you can hook up your integrations with this and have a clear overview of the popularity of something.

cc @dzaporozhets