Fix viewcontroller hierachy
We currently have the playbackcontroller as a childcontroller of the tabbarViewController but that's not a tabbaritem and it let to an invisible 6th tabbaritem before. This controller should instead not be childcontroller but we should have another controller that has the tabbarcontroller and playerviewcontroller in containerviews and would become the new rootviewcontroller. Right now the tabbarcontroller is our rootviewcontroller