Project object c14n in separte file

Create separate file for canonicalization of project factory objects and
introduce duplicate-diff lint checker.

tools/duplicate-diff.py

@@ -0,0 +1,33 @@
+#
+# Copyright 2025 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+import filecmp
+import sys
+
+duplicates = [
+    [
+        # "modules/net-vpc-factory/factory-projects-object.tf",
+        # data factory
+        "modules/project-factory/factory-projects-object.tf",
+    ],
+]
+
+for group in duplicates:
+  first = group[0]
+  for second in group[1:]:
+    if not filecmp.cmp(first, second):  # true if files are the same
+      print(f'found diff between {first} and {second}')
+      sys.exit(1)