Update tags empty states

What does this MR do and why?

• Show an empty state, when there are no tags
• Move page description to empty state, like on other pages
• Show empty state, then there are no search results

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Screenshots or screen recordings

Before	After

How to set up and validate locally

1. Create a project-1 project withing gitlab-org group
2. Visit /gitlab-org/project-1/-/tags
3. Add new tag
4. Go to tag list again
5. Search something

#424397 (closed)