TCK: Spec 329: Handle Group Validation of UISelectOne Elements

Discovered via TCK: https://github.com/jakartaee/faces/blob/c6d7d879065056978d74e5f486847fb203606203/tck/faces23/uiinput/src/test/java/ee/jakarta/tck/faces/test/javaee8/uiinput/Spec329IT.java#L38

Original Issue: https://github.com/jakartaee/faces/issues/329

There are a few various issues here, but the current failure is that no required messages are outputted if nothing is submitted.

An additional requirement is that only one required message should be outputted for a single group, not multiple (i.e. each uiselect one element).

Source of the problem is that we don't follow the spec for uiselectone#processValidators properly:

https://jakarta.ee/specifications/faces/4.0/apidocs/jakarta/faces/component/uiselectone#processValidators(jakarta.faces.context.FacesContext)

And we need to submit some value for the input, if it's left as null then validation is skipped entirely per the UIinput#validate spec.