Initialize native_call in agent host test fixtures (#58057)

Set `native_call` to `None` in the `ToolCall` and `ToolInvocation` fixtures used by the agent host invocation and spawn tests.

GitOrigin-RevId: 2a6f9ccb95d99297085a2861bb44e5ce7599715c

codex-rs/core/src/agent/host/invocation_tests.rs

@@ -85,6 +85,7 @@ async fn dispatch_revokes_access_and_holds_call_id_through_callbacks() -> anyhow
                     arguments: args.into(),
                 },
                 encrypted_function_args: None,
+                native_call: None,
             },
             source,
             token,

codex-rs/core/src/agent/host/spawn_tests.rs

@@ -112,6 +112,7 @@ async fn same_manager_creation_retains_step_executor_and_shares_exec_policy() ->
         payload: ToolPayload::Function {
             arguments: "{}".into(),
         },
+        native_call: None,
         environments: Default::default(),
     };
     let reservation = InvocationReservation::default();