Feature: Runner tag filter for admin view

What does this MR do?

• Adds a filter by tags to the admin runners view.
• Adds 1 new parameter to the runners API: tag_list

This MR depends on https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/19649.

Are there points in the code the reviewer needs to double check?

Why was this MR needed?

The admin runners view currently makes it hard to search for runners if there are a lot of runners.

One use case that this MR solves is that there should be way to find runners by tags. This allows for easier troubleshooting.

The development of this MR is sponsored by @ siemens (/cc @bufferoverflow).

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests added for this feature/bug
• Conform by the code review guidelines
  • Has been reviewed by a UX Designer
  • Has been reviewed by a Frontend maintainer
  • Has been reviewed by a Backend maintainer
  • Has been reviewed by a Database specialist
• Conform by the merge request performance guides
• Conform by the style guides
• If you have multiple commits, please combine them into a few logically organized commits by squashing them
• Internationalization required/considered
• End-to-end tests pass (package-and-qa manual pipeline job)

What are the relevant issue numbers?

Relates to https://gitlab.com/gitlab-org/gitlab-ce/issues/38504 and https://gitlab.com/gitlab-org/gitlab-ce/issues/36781.