Chore: move build command to importable package (#38726)

* move build command to importable package & clean up

pkg/build/exec.go

@@ -0,0 +1,34 @@
+package build
+
+import (
+	"bytes"
+	"log"
+	"os"
+	"os/exec"
+	"strings"
+)
+
+func runError(cmd string, args ...string) ([]byte, error) {
+	// Can ignore gosec G204 because this function is not used in Grafana, only in the build process.
+	//nolint:gosec
+	ecmd := exec.Command(cmd, args...)
+	bs, err := ecmd.CombinedOutput()
+	if err != nil {
+		return nil, err
+	}
+
+	return bytes.TrimSpace(bs), nil
+}
+
+func runPrint(cmd string, args ...string) {
+	log.Println(cmd, strings.Join(args, " "))
+	// Can ignore gosec G204 because this function is not used in Grafana, only in the build process.
+	//nolint:gosec
+	ecmd := exec.Command(cmd, args...)
+	ecmd.Stdout = os.Stdout
+	ecmd.Stderr = os.Stderr
+	err := ecmd.Run()
+	if err != nil {
+		log.Fatal(err)
+	}
+}