amd-efs#99 Improve dumping of image contents with unknown parts.

[daym]

See #99

[daym]

Not sure whether serde can be coaxed to continue even on serialization failure--and maybe even set a flag and fall back to something safe in that case.

Could always implement our own custom Serializer, I guess. It could just serialize the entire Result on each field, for example.

[daym]

We do implement our own serializer now (in amd-host-image-builder). It works just fine that way.

[wesolows]

Please don't wait for me; I don't understand this code and can't review it effectively. You have 2 capable reviewers already so if this checks out it can land.