[FSunstone] Redesign VM backup dialog

[vichansson]

Description

The current VM backup dialog is pretty lacking in context and might cause confusion due to this. It should be refactored so that more information is displayed to the user when creating a backup.

Interface Changes

Currently the backup dialog for a VM with an incremental backup chain

The dialog should be expanded to show information about these existing backups, like the Backup tab under the detailed view for the VM does

Progress Status

• [ ] Code committed
• [ ] Testing - QA
• [ ] Documentation (Release notes - resolved issues, compatibility, known issues)