How to create snapshot? --unimplemented

[qiao-summer]

`$ limactl snapshot create rocky-9 --tag "1111"

WARN[0000] limactl snapshot is experimental

FATA[0000] unimplemented`

[afbjorklund]

It is only available for vm type qemu at the moment

[mshlain]

i worked this out by:

1. shutdown vm
2. copy ~/.lima/default/basedisk to ~/lima_snapshot
3. copy ~/.lima/default/diffdisk to ~/lima_snapshot
4. start vm

restore works same way but copy from ~/lima_snapshot into ~/.lima/default