Nudasnev/shim get set vp state

[NunoDasNeves]

Summary of the PR

Make the get/set vp state IOCTLs simpler and easier to use. Remove any interpretation of the XSAVE state, as it is not needed for save/restore. Replace hv definitions in the interface with mshv definitions, so the kernel doesn't need to export these. Use a plain buffer for the data to simplify things.

Requirements

Before submitting your PR, please make sure you addressed the following 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.

[russell-islam]

I have been discussing this changes with @NunoDasNeves and we agreed on this. This PR looks good to me. @jinankjain @liuw Could you please look into this?

[liuw]

I have been discussing this changes with @NunoDasNeves and we agreed on this. This PR looks good to me. @jinankjain @liuw Could you please look into this?

I don't have a strong opinion on this. If the three of you agree on a way forward I'm fine with this PR.

[russell-islam]

@NunoDasNeves Please add missing Signed-off-by