Ability for self-service users to choose ticket entity

For self-service users there should be optional to be able to select what entity a new ticket should be created in (in the "simplified interface), in the same way that entity can be chosen in the "standard interface".

In that way, a user can have a single self-service role in a root entity with the benefit of being able to create and view tickets in all sub-entities without having to change entity in the upper right corner