Changes to Create a user

deleted the header request parameter IdempotencyKey

added the new optional header request parameter Idempotency-Key

the created_by response's property pattern was changed from ^[a-z]{3,7}_[0-9A-Za-z]{27}$ to ^[0-9A-Za-z_-]{1,255}$ for the status 200

the updated_by response's property pattern was changed from ^[a-z]{3,7}_[0-9A-Za-z]{27}$ to ^[0-9A-Za-z_-]{1,255}$ for the status 200