Add .NET code generation

[lukehoban]

Adds core code-generation support for .NET to the Kubernetes provider.

var pod = new Pulumi.Kubernetes.Core.V1.Pod("pod", new Pod
{
    Spec = new PodSpec
    {
        Containers = 
        {
            new Container
            {
                Name = "nginx",
                Image = "nginx",
            },
        },
    },
});

Part of #863.

[lukehoban]

Current build failures are due to the issue in the integration test framework being fixed in pulumi/pulumi#3527.

Fixed with 514f017.

[lukehoban]

@lblackstone @CyrusNajmabadi @mikhailshilkov @hausdorff @pgavlin This now ready for review. Tests are passing for the Guestbook example.

[mikhailshilkov]

Great to see this coming! I left several small comments.

[CyrusNajmabadi]

Skimmed over this and nothing looks out of place or concerning. If you have any particular areas you'd like me to look more deeply at, just call them out. But, otherwise, if this works then this works :)

[lblackstone]

LGTM - It looks correct as far as I can tell, but the syntax on the example is pretty hideous. Guessing there's no way around that while maintaining strong typing.