ChaCha20 encryption with Argon2 key derivation support

[ha3ext]

Dear @cternes,

According to https://keepass.info/help/base/security.html the "ChaCha20 is the successor of the Salsa20 algorithm" and KeePass 2.x supports it.

According to the source, openkeepass supports KeePass 2.x and Salsa20 algorithm.

Proposal of the User Story description:
As an openkeepass user, I would like to use KeePass 2.x database files with the following configurations:

• ChaCha20 encryption with Argon2 key derivation key
• AES/Rijandael encryption with Argon2 key derivation key

Proposal unit tests for the User Story:
ha3ext@4e199d1

I am looking forward to your reply.

Thank you!

Sincerely,
Attila Horvath
Software Engineer
Digitalization

[sorz]

ChaCha20 and Argon2 were added in KDBX 4, which also has other changes in the file format.
https://keepass.info/help/kb/kdbx_4.html