utils/file: Create files as running user instead of effective user

Author: vista-

utils/file.go

@@ -156,6 +156,12 @@ func CopyFileContents(src, dst string, mode os.FileMode) (err error) {
 		return err
 	}
 
+	// Change file ownership to user running Containerlab instead of effective UID
+	err = SetUIDAndGID(dst)
+	if err != nil {
+		return err
+	}
+
 	err = out.Chmod(mode)
 	if err != nil {
 		return err
@@ -196,6 +202,12 @@ func CreateFile(file, content string) (err error) {
 		return err
 	}
 
+	// Change file ownership to user running Containerlab instead of effective UID
+	err = SetUIDAndGID(file)
+	if err != nil {
+		return err
+	}
+
 	return f.Close()
 }