KRACOEUS-7308: JPA work for budget

Good question and one we maybe should discuss. I assumed we were moving common.budget to primarily abstract classes with propdev and award defining concrete versions as necessary or always. This allows common services to be defined in common.budget and can allow propdev and award budget to extend/modify those as necessary as well. So the reason I ask is now in this model we'll have AbstractBudget and then another abstract Budget class and then finally ProposalBudget and AwardBudget inheriting from it? Obviously there are additional technical problems here, like adding discriminator columns or moving to single table inheritance. @geothomasp any other thoughts?