Add BigInteger Implementation to Factorial.java

[antailbaxt3r]

he previous implementation of Math/Factorial.java involved usage of long datatypes that have large storage, but it cannot even handle 100 factorial. Hence java.math.BigInteger implementation is required.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[stale]

Please reopen this issue once you add more information and updates here. If this is not the case and you need some help, feel free to seek help from our Gitter or ping one of the reviewers. Thank you for your contributions!