Initial provider implementation (#18)

This brings over the initial buildx prototype from pulumi/pulumi-docker
and fixes various build and release issues.

sdk/nodejs/config/index.ts

@@ -0,0 +1,5 @@
+// *** WARNING: this file was generated by pulumi-language-nodejs. ***
+// *** Do not edit by hand unless you're certain you know what you are doing! ***
+
+// Export members:
+export * from "./vars";