CI: Make pkg/build its own module, remove unused Grafana modules in go.mo… (#89243)

* Make pkg/build its own module, remove unused Grafana modules in go.mod/go.sum

* fix go.work format

* log errors on file close errors

pkg/plugins/codegen/package_json.go

@@ -0,0 +1,33 @@
+package codegen
+
+import (
+	"encoding/json"
+	"log"
+	"os"
+	"path/filepath"
+)
+
+type PackageJSON struct {
+	Version string `json:"version"`
+}
+
+// Opens the package.json file in the provided directory and returns a struct that represents its contents
+func OpenPackageJSON(dir string) (PackageJSON, error) {
+	f, err := os.Open(filepath.Clean(dir + "/package.json"))
+	if err != nil {
+		return PackageJSON{}, err
+	}
+
+	defer func() {
+		if err := f.Close(); err != nil {
+			log.Println("error closing package.json", err)
+		}
+	}()
+
+	jsonObj := PackageJSON{}
+	if err := json.NewDecoder(f).Decode(&jsonObj); err != nil {
+		return PackageJSON{}, err
+	}
+
+	return jsonObj, nil
+}