fix: store execution before invoke

- persist execution object before we send the invoke request to lambda side

Author: Alex Wang

src/aws_durable_execution_sdk_python_testing/executor.py

@@ -646,6 +646,8 @@ async def invoke() -> None:
                     self._invoker.create_invocation_input(execution=execution)
                 )
 
+                self._store.save(execution)
+
                 response: DurableExecutionInvocationOutput = self._invoker.invoke(
                     execution.start_input.function_name, invocation_input
                 )