[COLLECTIONS-795] Add PairedIterator to allow iterating over different-types of iterators

[anantdamle]

[COLLECTIONS-795] Add a new Iterator to allowing zipping over two iterators of different types

This is different from ZippingIterator which only permits sub-iterators of same type.
Created as #238 was overwhelmed with multiple commits due to inactivity for 2+ years.

@garydgregory can you please consider this proposal

[Claudenw]

@anantdamle I had a professor who stated there are only 3 valid limits in computing: zero, one, and many. Your solution zips two iterators, have you considered who to generalize that to many? Is that possible?

[anantdamle]

also fixed it in PairedIterableTest.java

[anantdamle]

@anantdamle I had a professor who stated there are only 3 valid limits in computing: zero, one, and many. Your solution zips two iterators, have you considered who to generalize that to many? Is that possible?

I think Its possible, and I have tried it, with a working prototype, though the interface becomes too complex as the consitutents can be of different kind (classes), so will have to use Object and class type, which in my opinion becomes a bad design.

class MultiZipIterator implements Iterator<List<Pair<Object, Class>>> 

[Claudenw]

LGTM
After running the tests, there are a number of issues with style. @anantdamle please run mvn on your local branch and you should see a number of style issues as highlighted in the CI test runs.

[Claudenw]

Plese fix error reported by CI test.

[anantdamle]

@Claudenw thanks for reviewing this, fixed checkstyle formatting issues.

[garydgregory]

@anantdamle
I added a few low-level comments.

[anantdamle]

@garydgregory made changes as requested and rebased on latest master

[anantdamle]

Gentle bump up for review