Move to project dropdown with infinite scroll for better performance
## What does this MR do?
On the Move dropdown on the edit issue page we introduced infinite scrolling to just return a limited number of projects, 50 items. So if the user can move the issue to 50 or more items when scroll down on the list a new set of projects will be requested to the server.
## Are there points in the code the reviewer needs to double check?
## Why was this MR needed?
See #17932
## What are the relevant issue numbers?
Closes #17932
## Screenshots (if relevant)
## Does this MR meet the acceptance criteria?
- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- ~~[ ] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)~~
- ~~[ ] API support added~~
- Tests
- [x] Added for this feature/bug
- [x] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)
See merge request !5686
