Check Slug Availability

{  "available": true,  "reason": "string"}

{  "_tag": "ProjectValidationError",  "message": "string"}

{  "_tag": "UnauthorizedError",  "message": "string"}

{  "_tag": "ForbiddenError",  "message": "string",  "code": "string"}

{  "_tag": "NotFoundError",  "message": "string"}

{  "_tag": "ProjectConflictError",  "message": "string"}