Set the priority to the passed pubkey over the authentication method for `balance` and `checksum` cmds

Commands allowing to pass a pubkey via the authentication and the usual CLI (balance and checksum for now) are prioritizing the authentication methods over the pubkey. @matograine suggested to prioritize the pubkey over the authentication method or return an error.

That could be an issue when silkaj -af is set as a shell alias, where the authentication would always be set on every command, then the user would forget about it, and get the result for public key from the authentication file.