Allow setting the owner, group and mode of the `/dev/sev-guest` device,
similar to what is already possible for `/dev/sev` through the
`hardware.cpu.amd.sev` options.
The `/dev/sev` device is available to AMD SEV hosts, e.g., to start an
AMD SEV-SNP guest. In contrast, the `/dev/sev-guest` device is only
available within SEV-SNP guests. The guest uses the device, for example,
to request an attestation report. Linux has in-tree support for SEV-SNP
guests since 5.19.
e22dff17f5