Revert "Test: 10,000"

Before I refactor those duplicated data, let's go back to the statement
-> recursion transformation (case 121) and see if there is a better
transformation I could go with.

This reverts commit dded559e2b11e8c8c4a0e37a19e99403cb957126.
Revert "Test: add more cases, 2000 - 9000"

This reverts commit b60eb30cc26ab0ed8ed80d9688bfe4a295903f26.
Revert "Test: 1000"

This reverts commit 8917711a472033f72f40cbcc430a6705e0c41254.
Revert "Test: add more cases for three digits convert to one number string with two words"

This reverts commit d23ddfa4f9a544ae8c6e06bd7681deaa31838aaa.
Test: add more cases for three digits convert to one number string with two words
TPP: constant -> constant+
Let's see the duplication data first by transform the code with a quite low transformation.
The duplicated data (NUMBER_STRINGS key-value pairs for 100 - 900) is refactored into an "if" condition (the new execution path is a recursive call)
At this point, it's hard to say whether this refactoring is good or not. Let's see how it goes.
Test: four digits convert to one number string with two words
TPP: unconditional -> if (the new execution path is a recursive call)
Still a low priority in TPP list comparing to constant -> constant+. However, I see no data duplication in NUMBER_STRINGS and a chance to convert those two similar "if" for 100s and 1000/2000 to a general code. Let's see.
Test: four digits in general
TPP: expression (in fact, constant) -> function (100 -> closestCountingUnitNumber), but there is reverse TPP: recursive -> statement (no more recursive in the final return)
One important refactoring is, by the reverse TPP, convertInsideCountingUnit is extracted, which has no recursive inside
This interesting transformation will make me rethink the TPP steps of this Kata next time