Resolve "Group dashboard UI"

What does this MR do?

Updates dashboard/groups page UI with better support of subgroups

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

no

Why was this MR needed?

To improve visual experience when working with subgroups from dashboard/groups page

Screenshot

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• 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 #25426 (closed)

Frontend Task list

• Layout

• CSS/HTML for dashboard/groups page

• Functionality

• Support pagination

• Filter by name

• Filter by options from dropdown

• Filter by query strings passed via URL when page loads

• Load subgroups on demand

• Tests

• Feature tests

• Unit tests