Issues empty state

What does this MR do?

Adds the empty state for the project, dashboard and group issues.

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

Why was this MR needed?

Screenshots (if relevant)

Filtered to show no issues (on group issues page in this case but also dashboard and projects)

Project with no issues

Group with no projects with any issues

Does this MR meet the acceptance criteria?

• Changelog entry added
• Documentation created/updated
• API support added
• Tests
  • Added for this feature/bug
  • All builds are passing
• Conform by the merge request performance guides
• Conform by the style guides
• Branch has no merge conflicts with master (if it does - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

Closes #20840 (closed)

Closes #20850 (closed)