Create new JavaType subtype IterationType (extending SimpleType)

[cowtowncoder]

(note: possible replacement/impl of #3926)

There are benefits in recognizing types like:

• Iterator
• Stream
• DoubleStream / IntStream / LongStream

as first-class JavaType variants (see FasterXML/jackson-dataformat-xml#597 f.ex).
It should be based on SimpleType, similar to ReferenceType.

If and when implemented we could consider whether to extend Deserializers, Serializers and other extension points.
Also: would need to add support by Scala module, possibly Kotlin (and maybe Guava?).

[cowtowncoder]

@pjfanning Now implemented for core JDK types as per description. Might make sense to add support by Scala module too?

@JooHyukKim Should be possibly to use the new JavaType.isIterationType() method from XML module to simplify checking (plus support Scala iterators too if and when support added).

[JooHyukKim]

@cowtowncoder Great 👍🏻🔥 I will try to apply the changes accordingly.