add id_for_file_path helper method for process groups

spiffworkflow-backend/src/spiffworkflow_backend/models/process_group.py

@@ -10,6 +10,8 @@ import marshmallow
 from marshmallow import post_load
 from marshmallow import Schema
 
+import os
+
 from spiffworkflow_backend.models.process_model import ProcessModelInfo
 
 
@@ -47,6 +49,11 @@ class ProcessGroup:
         original_dict = dataclasses.asdict(self)
         return {x: original_dict[x] for x in original_dict if x not in ["sort_index"]}
 
+    # for use with os.path.join, so it can work on windows
+    def id_for_file_path(self) -> str:
+        """Id_for_file_path."""
+        return self.id.replace("/", os.sep)
+
 
 class ProcessGroupSchema(Schema):
     """ProcessGroupSchema."""