KRACOEUS-7645 : Fix BudgetPerson JPA mapping and modify DocNextvalue

Pay particular attention to the DocumentNextvalue changes in this PR. I've put them out there
primarily for comment at this point since they are fairly drastic. In order to persist DocumentNextvalues with the first saving of the budget we can't map the documentKey column or else it will fail to persist. By removing the annotation JPA will auto-populate the foreign key based on the OneToMany relationship definition. The only alternative I see to this is to make sure we never try to persist DocumentNextvalues during the initial save of the budget.