Display the id, name, username and email of the creator of a new project in the webhook data

What does this MR do?

Adds extra fields about the creator of a project in the system webhook sent on projects events.

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

Why was this MR needed?

Fixes the feature request #35597 (moved) In summary, this will allow us to automate some processes around repository creation as it would allow us to know who created the repository to send him actionable links via slack/emails.

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
  • All builds are passing
• 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
• Branch has no merge conflicts with master (if it does - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

#35597 (moved)