Introduce deployment services, starting with a KubernetesService

What does this MR do?

Adds a minimal KubernetesService and introduces the idea of deployment services, generally.

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

Why was this MR needed?

Two issues scheduled for 8.15 both require a Kubernetes service - #22864 (closed) and #23580 (closed) - but they use it for very different things. Add a minimal kubernetes service to avoid conflicts later.

Screenshots

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 #22985 (closed)