V2 - Slight change in behavior for endpoints attempting to create a treasury Category without a `direction`

Slight change in behavior for endpoints attempting to create a Category record:

• when not including a direction string in the Category creation request for a treasury family, it will be automatically assigned the direction cash_out, without any errors

The rest of the functionality will remain the same. For example, when creating a non-treasury Category with a direction it will still be an error scenario.