[Hyper-V Extension] Change KVP names in Hyper-V Host-Guest communication.

[sshilov7]

Summary of the pull request

Previous implementation of communication between host and guest Hyper-V machine using Hyper-V KVP integration service was not deleting KVPs correctly. KVPs created on host side must be delete from host. When they are only deleted from guest side (as registry keys) they are re-created after Hyper-V VM reboot.

In addition, Hyper-V KVP integration service has a limit (undocumented) on number of KVP and after exceeding that limit no new keys can be created. KVP service API doesn't allow reading We used GUID in the key names.

This fix changes KVP name format: instead of using GUID ("DevSetup{}") it's now a sequential number ("DevSetup{}") to make KVP names more predictable. In case we run into a situation where we have stale KVPs, some of them can be re-used (and then deleted), reducing chances of reaching max number of KVPs limit.
Under normal operation these KVPs deleted after communication with guest machine is complete or KvpSession object is disposed.

Added a new GetState request to get DevSetupAgent service state. For now, it returns a list of requests in queue. Host side won't send new requests if queue is not empty (this flow will need improvements in the future. We don't have UX for it yet)

Added a test for GetState request.

Updated current tests to use new format of KVP names.

Fixed copying of Microsoft.Windows.DevHome.DevSetupEngine.winmd into test projects output.

References and relevant issues

Validation steps performed

Ran tests and Hyper-V configuration flow.

PR checklist

• Closes #xxx
• Tests added/passed
• Documentation updated