Snapshots of Hyper-V VMs fail to restore after the daemon restarts

[ricab]

Describe the bug
The constructor for Hyper-V snapshots that are loaded from disk leave a field uninitialized. That field is used to command Hyper-V to restore them. Consequently, restoring such snapshots fails.

To Reproduce
How, and what happened?

1. multipass snapshot -n s1 <instance>
2. restart daemon
3. multipass restore -vvvv <instance>.s1

Expected behavior
Snapshots would restore normally.

Logs
Please provide logs from the daemon, see accessing logs on where to find them on your platform.

Additional info

• OS: Windows
• multipass version: 1.13.1
• multipass get local.driver: hyper-v