add extra single arg deser tests

[pjfanning]

• related to Review of number deserialization #4484
• doesn't fix anything but adds extra regression coverage

These tests only pass because the mapper used has this:

    @Target(ElementType.PARAMETER)
    @Retention(RetentionPolicy.RUNTIME)
    public @interface ImplicitName {
        String value();
    }

    public class ImplicitNameIntrospector extends JacksonAnnotationIntrospector
    {
        @Override
        public String findImplicitPropertyName(AnnotatedMember member) {
            final ImplicitName ann = member.getAnnotation(ImplicitName.class);
            return (ann == null) ? null : ann.value();
        }
    }

ObjectMapper mapper = JsonMapper.builder()
                .annotationIntrospector(new ImplicitNameIntrospector())
                .constructorDetector(ConstructorDetector.USE_PROPERTIES_BASED)
                .build();

[cowtowncoder]

LGTM, thanks!