Replace the string interpolation examples

[jaxxstorm]

Lots of the examples in this repo use string interpolation to build YAML or JSON documents, especially around generating kubeconfig files. A few examples I could find:

https://github.com/pulumi/examples/blob/fd422a115ca1602eed9a895ab4ed748185d798cc/aws-go-eks/main.go#L227 https://github.com/pulumi/examples/blob/90f6fa541f7d6cf0b5171b39e7ef234b785cc98f/aws-cs-eks/EksStack.cs#L14-L52

Unfortunately, this is error-prone, and we've had several examples of users copying and pasting these examples and creating typos, which bubble up into weird errors and are hard to debug.

It would be great if we could move this into the native language JSON/YAML encoding, so we can catch errors and stop the proliferation of these requests