Changes to POST /practice-simulation-assignments

added the optional property code to the response with the 400 status

added the optional property code to the response with the 403 status

added the optional property code to the response with the 404 status

added the optional property code to the response with the 409 status

added the optional property code to the response with the 502 status

added the optional property code to the response with the 503 status

added the required property data/items/assigned_by_name to the response with the 201 status

added the required property data/items/best_attempt/outcome to the response with the 201 status

added the required property data/items/last_active_at to the response with the 201 status

added the required property data/items/last_attempt/outcome to the response with the 201 status

added the required property data/items/simulation_apps to the response with the 201 status

endpoint added