Add Windows Server Container Support (WCOW with process isolation)

[Random-Liu]

The windows server container support in containerd is close to ready. Let's add the support into the CRI plugin.

We had some initial discussion with @jterry75, and decided to support WCOW (windows container on windows) with process isolation only (non HyperV) as the first milestone.

The discussion can be found at https://docs.google.com/document/d/1PKlmTIh0-qSzGDPhYmc_5BJjdD9GRdMGIATzvlhUAwM/edit#heading=h.qzvxb8bbb31y

@containerd/containerd-maintainers

[Random-Liu]

After #1264 is merged, we will have basic WCOW process isolation support on windows. After that is done, we still have the following working items:

• Support portforward
• Support container compute stats
• Support snapshot stats including ImagefsInfo and writable layer size
• Apply CPU shares to sandbox
• Add CredentialSpec support (Ref Implement gMSA support in V2 schema microsoft/hcsshim#347)
• Benchmark and optimize image pull. Containerd pulling windows image seems to be super slow.
• Support live-restore.

[yliaog]

/cc