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/dotnet_test.go

@@ -0,0 +1,39 @@
+//go:build dotnet || all
+// +build dotnet all
+
+package examples
+
+import (
+	"os"
+	"os/exec"
+	"path"
+	"path/filepath"
+	"testing"
+
+	"github.com/pulumi/pulumi/pkg/v3/testing/integration"
+	"github.com/stretchr/testify/require"
+)
+
+func TestDotNetExample(t *testing.T) {
+	cwd, err := os.Getwd()
+	require.NoError(t, err)
+
+	nuget := filepath.Join(cwd, "../nuget")
+	t.Setenv("PULUMI_LOCAL_NUGET", nuget)
+
+	cmd := exec.Command("dotnet", "nuget", "add", "source", nuget)
+	_ = cmd.Run()
+
+	test := integration.ProgramTestOptions{
+		Dir: path.Join(cwd, "dotnet"),
+		Dependencies: []string{
+			"Pulumi.Dockerbuild",
+		},
+		Secrets: map[string]string{
+			"dockerHubPassword": os.Getenv("DOCKER_HUB_PASSWORD"),
+		},
+		NoParallel: true,
+	}
+
+	integration.ProgramTest(t, &test)
+}