Added support for execution simple MULTISCAN command (only one file)

[roldevg]

Hi all!

We are using antivirus as a service, but we need to scan file by the path on the shared volume.
I think this feature will be useful for other users of clamav-java.

Notes for PR:

1. I couldn't add a file with standard virus signature for tests, because it's an alarm for antiviruses :)
2. It's needed to create a new image for green tests (healthy.file), but building image does not exist into CI pipeline now (docker pull lokori/clamav-javal). I can add, is it needed?