UIInput<?> should support setValidator(UIIInputValidator) getValidator() for input-level-validation

Currently Forge 2 UI API supports command-level validation, but we don't support field-level validation, which would be useful for dev simplification/ease of use.

This may or may not be able to live on the base InputComponent interface, but more likely it will need to be customized for each of UISelectOne, UISelectMany, UIInput, and UIInputMany types.

public interface InputComponent<IMPLTYPE, VALUETYPE> extends Faceted<HintsFacet>
{

   Validator<VALUETYPE> getValidator();

   IMPLTYPE setValidator(Validator<VALUETYPE>);

}