Add Argon2Kdf and enable parameters in db settings

Note: This implementation is not yet connected to the
database itself and will corrupt existing kdbx3 db's.

* Implemented memory and parallelism parameters for Argon2Kdf
* Using libargon2; libsodium does not support Argon2d algorithm
* Moved basic rounds parameter into Kdf class
* Reimplemented benchmark algorithm; previous was utterly broken

src/format/KeePass2.h

@@ -40,6 +40,7 @@ namespace KeePass2
     extern const Uuid CIPHER_CHACHA20;
 
     extern const Uuid KDF_AES;
+    extern const Uuid KDF_ARGON2;
 
     extern const QByteArray INNER_STREAM_SALSA20_IV;