Re-implement: Qemu EFI disk

[Tinyblargon]

EFI should use the following struct. When the value is nil we wont change the value in PVE, this means that for updates we need to know the current settings.

type QemuEfiDisk struct {
	Delete        bool            `json:"delete,omitempty"`
	Storage       *string         `json:"storage,omitempty"`         // required during creation
	Format        *QemuDiskFormat `json:"format,omitempty"`          // required during creation
	PreEnrollKeys *bool           `json:"pre_enroll_keys,omitempty"` // changing recreates the disk
}