Our checkpoint file is now in a shape such that go's built in
marshalling and unmarshalling is sufficent, so we can remove the code
we had on our decode path to do extra validation
This includes a few changes:
* The repo name -- and hence the Go modules -- changes from pulumi-fabric to pulumi.
* The Node.js SDK package changes from @pulumi/pulumi-fabric to just pulumi.
* The CLI is renamed from lumi to pulumi.