Initial provider implementation (#18)

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

sdk/go/dockerbuild/x/config/config.go

@@ -0,0 +1,28 @@
+// Code generated by pulumi-language-go DO NOT EDIT.
+// *** WARNING: Do not edit by hand unless you're certain you know what you are doing! ***
+
+package config
+
+import (
+	"github.com/pulumi/pulumi-docker-build/sdk/go/dockerbuild/internal"
+	"github.com/pulumi/pulumi/sdk/v3/go/pulumi"
+	"github.com/pulumi/pulumi/sdk/v3/go/pulumi/config"
+)
+
+var _ = internal.GetEnvOrDefault
+
+// The build daemon's address.
+func GetHost(ctx *pulumi.Context) string {
+	v, err := config.Try(ctx, "docker-build:host")
+	if err == nil {
+		return v
+	}
+	var value string
+	if d := internal.GetEnvOrDefault("", nil, "DOCKER_HOST"); d != nil {
+		value = d.(string)
+	}
+	return value
+}
+func GetRegistries(ctx *pulumi.Context) string {
+	return config.Get(ctx, "docker-build:registries")
+}