Add ui state to JsonFormsSubStates for server error filtering

While it is currently possible to override the controls, to change how they behave, this is not always feasible/sensible.

We use the vuetify form controls and render all errors on the server. It would be practical to have the ui state (focused, touched, pristine, …) of the fields available outside a JsonForms component, so we can filter the data sent to the server or filter the errors coming from the backend, to hide errors on pristine fields.

If writing custom renderers is too much effort for you, you could consider contributing this functionality directly to JSON Forms. In this case I would like to recommend to open an issue in the repository first, outlining the functionality in detail which you would like to see. This way we can give feedback whether we would accept such a contribution before you actually start implementing it.