Shortest coprime segment using sliding window technique (#6296)

* Shortest coprime segment using sliding window technique

* mvn checkstyle passes

* gcd function reformatted

* fixed typo in ShortestCoprimeSegment

* 1. shortestCoprimeSegment now returns not the length, but the shortest segment itself.
2. Testcases have been adapted, a few new ones added.

* clang formatted ShortestCoprimeSegmentTest.java code