Add project creation API endpoint

[AdrianoKF]

Goals:

• Create data model for projects
• Implement POST /projects API endpoint

Implementation notes:

• We should prevent the deletion of Kubernetes resources through custom finalizers, to prevent dangling references from projects to Kubernetes resources.

Open questions:

• Does the caller specify existing Kueue name and namespace? Probably not. What happens if the names clash with existing Kubernetes resources?