WIP: 46538 refactor member service

What does this MR do?

Refactor the Create service into another service, and move the add_user from the member model into the create service.

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

The api and the UI should both be getting logged through the create service.

Why was this MR needed?

Tech debt + This will make it easier to complete: 30791

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests added for this feature/bug
• Conform by the code review guidelines
  • Has been reviewed by a UX Designer
  • Has been reviewed by a Frontend maintainer
  • Has been reviewed by a Backend maintainer
  • Has been reviewed by a Database specialist
• Conform by the merge request performance guides
• Conform by the style guides
• If you have multiple commits, please combine them into a few logically organized commits by squashing them
• Internationalization required/considered
• End-to-end tests pass (package-and-qa manual pipeline job)

What are the relevant issue numbers?

#46538 (moved)