Housekeeping (#8)

* Rename the provider to dockerbuild.
* Add Makefile targets required by CI.
* Add per-language test targets compatible with CI.
* Fix broken example yaml.
* Add gitignore exclusions to fix SDK generation in CI.
* Fix lint errors.
* Vendor pulumi CLI via `tools.go` instead of `.pulumi`.
* Consolidate `go.mod`s into one file, with a minimal `go.mod` for the
Go SDK.
* Add codecov.

examples/nodejs_test.go

@@ -0,0 +1,28 @@
+//go:build nodejs || all
+// +build nodejs all
+
+package examples
+
+import (
+	"os"
+	"path"
+	"testing"
+
+	"github.com/pulumi/pulumi/pkg/v3/testing/integration"
+	"github.com/stretchr/testify/require"
+)
+
+func TestNodeExample(t *testing.T) {
+	cwd, err := os.Getwd()
+	require.NoError(t, err)
+
+	test := integration.ProgramTestOptions{
+		Dir:          path.Join(cwd, "nodejs"),
+		Dependencies: []string{"@pulumi/dockerbuild"},
+		Secrets: map[string]string{
+			"dockerHubPassword": os.Getenv("DOCKER_HUB_PASSWORD"),
+		},
+	}
+
+	integration.ProgramTest(t, &test)
+}