cargo.build, the WASI test runner, the console, and core.notify ordering

- cargo.build (native): one source copy, tests under WASI, release
  build to /state/cargo/builds/<n>/, process groups killed on cancel.
  The host writes the SDK copy to /plugins/cargo/sdk/ at start.
- sausage test-runner: one instance per test, in parallel, with its own
  mount table (empty world, package folder at its path); answers
  core.lock, core.unlock, core.notify, core.log.
- The console: rustyline, notifications while typing, ls/cat through the
  process view, methods, ps, log, activate, revert, stop, kill.
- core.notify on stdout is handled in order, before the response.

cli/tests/core.rs

@@ -243,6 +243,34 @@ async fn progress_notifications_reach_the_caller() {
     h.stop().await;
 }
 
+/// PROTOCOL 3.5: every stdout notification reaches the caller before the following result.
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn stdout_notifications_precede_the_result() {
+    let w = TestWorld::new();
+    let h = w.start().await;
+    let mut notifications = h.subscribe();
+    for _ in 0..10 {
+        assert_eq!(call(&h, "probe.burst", json!({"count":64})).await, 64);
+        let mut call_id = None;
+        for index in 0..64 {
+            // A delayed notification fails here, even if it arrives later.
+            let notification = notifications.try_recv().unwrap();
+            assert_eq!(notification["params"]["name"], "burst");
+            assert_eq!(notification["params"]["params"]["index"], index);
+            if let Some(id) = &call_id {
+                assert_eq!(&notification["params"]["call"], id);
+            } else {
+                call_id = Some(notification["params"]["call"].clone());
+            }
+        }
+        assert!(matches!(
+            notifications.try_recv(),
+            Err(tokio::sync::broadcast::error::TryRecvError::Empty)
+        ));
+    }
+    h.stop().await;
+}
+
 /// PROTOCOL 3.1: non message stdout warns once without its content.
 #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
 async fn non_message_stdout_warns_once_without_its_content() {