Re-implement: Qemu Unused Disks

[Tinyblargon]

UnusedDisks should use the following structure. When the value is nil we wont change the value in PVE, this means that for updates we need to know the current settings. Modifying the disk when it does not exist should give an error during the Validation phase.

type QemuUnusedDisks map[QemuUnusedDiskID]QemuUnusedDisk

type QemuUnusedDisk struct {
	Delete  bool            `json:"delete"`
	Storage *string         `json:"storage,omitempty"` // Changing migrates the disk to a different storage
	Format  *QemuDiskFormat `json:"format,omitempty"`  // Changing the format of the disk
}

type QemuUnusedDiskID uint8