init: added backend boilerplate

services/backend/config/errors.py

@@ -0,0 +1,13 @@
+from http import HTTPStatus as status
+
+from django.core.exceptions import ValidationError
+
+
+class ConflictError(Exception):
+    def __init__(self, validation_error: ValidationError) -> None:
+        self.validation_error = validation_error
+
+
+class ForbiddenError(Exception):
+    def __init__(self, message: str = status.FORBIDDEN.phrase) -> None:
+        self.message = message