Add ChaCha20-Poly1305 Support for OpenSSH Keys

[exceptionfactory]

This pull request adds support for the chacha20-poly1305@openssh.com cipher when decrypting OpenSSH Private Keys.

The implementation required adjusting the ChachaPolyCipher.update() method to accept an input offset of 0, indicating no Additional Authenticated Data included with the encrypted bytes.

[codecov-commenter]

Codecov Report

Merging #904 (32b4e12) into master (3b67d2b) will decrease coverage by 0.02%.
The diff coverage is 92.85%.

@@             Coverage Diff              @@
##             master     #904      +/-   ##
============================================
- Coverage     68.45%   68.44%   -0.02%     
+ Complexity     1402     1400       -2     
============================================
  Files           207      207              
  Lines          7475     7478       +3     
  Branches        630      631       +1     
============================================
+ Hits           5117     5118       +1     
- Misses         2023     2024       +1     
- Partials        335      336       +1     

Files	Coverage Δ
...sshj/userauth/keyprovider/OpenSSHKeyV1KeyFile.java	86.45% <100.00%> (+0.07%)	⬆️
...ynomus/sshj/transport/cipher/ChachaPolyCipher.java	77.94% <91.66%> (+0.66%)	⬆️

... and 8 files with indirect coverage changes