Add new encoding: vigenere

### Description

_Method of encrypting alphabetic text by using a series of interwoven Caesar ciphers based on the letters of a keyword. Though the 'chiffre indéchiffrable' is easy to understand and implement, for three centuries it resisted all attempts to break it._

Source: [Cryptii](https://cryptii.com/pipes/vigenere-cipher)

### Reference

https://en.wikipedia.org/wiki/Vigen%C3%A8re_cipher