kvm-ioctls: backport kvm nested state to v0.22.1

[phip1611]

This is a backport of #322 [0] from the latest state to v0.22.1 to enable an easy way to use this in cloud-hypervisor by simply bumping the patch version of the component.

The backport is done in two steps, this is step 2/2. This commit only does the necessary steps for kvm-ioctls.

[0] #322

Summary of the PR

Please summarize here why the changes in this PR are needed.

Requirements

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requirements:

• All commits in this PR have Signed-Off-By trailers (with
  git commit -s), and the commit message has max 60 characters for the
  summary and max 75 characters for each description line.
• All added/changed functionality has a corresponding unit/integration
  test.
• All added/changed public-facing functionality has entries in the "Upcoming
  Release" section of CHANGELOG.md (if no such section exists, please create one).
• Any newly added unsafe code is properly documented.

[roypat]

heh, something weird is going on with the serde feature in CI, could you look into that? :o

[phip1611]

I have absolutely no clue what is going on there... I assume some Rust edition 2015 glitch. I'm looking for a workaround

[snue]

heh, something weird is going on with the serde feature in CI, could you look into that? :o

This is failing for the kvm-bindings build of the workspace, because the explicitly requested features do not have fam-wrappers, only serde. This was not an issue when the kvm-ioctls build requested the feature from the kvm-bindings crate of the workspace, but now it consumes directly from crates.io, and nothing forces the feature on the workspace build. You can see it uses both versions (0.12.1 and 0.12.0 from workdir) in the log.

https://buildkite.com/rust-vmm/kvm-ci/builds/1463/steps/canvas?jid=01995738-26ed-4e8c-9e14-c3f23d6de434