VMCloak - add interactivity for vmcloak init

[cert-ee-raidar]

Feature

VMCloak init command should be interactive in case of errors.

Proposed solution

Redo functionality so that when VMCloak discovers the image with same name, it will prompt "override" or "rename" the file.

• "override" option will delete the old qcow2 image and create a new one
• "rename" option prompts for new name for the qcow2 image and creates a new qcow2 image with that name

Additional context

When running vmcloak multiple times with same qcow2 image name, it exits with ValueError.