The `Checkpoint` type should not be dependent on third-party libraries

[nojnhuh]

The Checkpoint type which is serialized and persisted to disk is in part composed of third-party types:

• drapbv1.Device
• cdiapi.ContainerEdits

If these types were to subtly change as a result of a dependency update, the format the driver serializes may become incompatible with prior versions and break driver upgrades. The driver should define these types wholly itself to guard against this.

We should define sufficiently equivalent types for the ones listed above and leverage conversion-gen if possible to convert to the third-party types expected by the kubelet and make incompatible changes which need to be handled manually more visible.

[pohly]

Depending on a v1 type which is explicitly meant to be serialized via JSON is okay as long the upstream can be trusted to uphold the API stability. The problem with the kubelet checksuming code was that it checksums the go-spew output of the in-memory representation and that output changed when new fields got added.

https://pkg.go.dev/tags.cncf.io/container-device-interface@v0.8.0/pkg/cdi#ContainerEdits is not a v1 type, so we shouldn't depend on it.