[Req] add javax/jakarta validator for Present

[jpfinne]

Add the @Present annotation mentioned in handling of openapiNullable+required

Sample code:

public class PresentValidator implements ConstraintValidator<Present, JsonNullable<?>> {
    @Override
    public boolean isValid(JsonNullable<?> value, ConstraintValidatorContext context) {
        return value != null && value.isPresent();
    }
}