Add loading state to similar issues
Problem to solve
The loading state that was originally designed for https://gitlab.com/gitlab-org/gitlab-ce/issues/22071 took vertical space below the input, disappearing right after if there weren't any results.
Further details
It's important to give some feedback to the user that there's background activity (searching for issues), while not taking precious vertical space.
Proposal
One possibility is to add a spinner to the input while communicating with the server:
What does success look like, and how can we measure that?
(If no way to measure success, link to an issue that will implement a way to measure this)