Refactor/group links controller

What does this MR do?

Refactor the create and destroy actions in the GroupLinksController

Why was this MR needed?

I need and an extension point for this actions in EE. Later on, I will prepend an EE Service into these new services.

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests added for this feature/bug
• Review
  • Has been reviewed by UX
  • Has been reviewed by Frontend
  • Has been reviewed by Backend
  • Has been reviewed by Database
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together