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/plugins/probe/src/main.rs

@@ -14,6 +14,13 @@ fn receive(lines: &mut Lines) -> Value {
 fn echo(params: &Value) -> Value {
     params.clone()
 }
+fn chat(params: &Value) -> Value {
+    send(json!({"jsonrpc":"2.0", "method":"core.notify", "params":{
+        "name":"text", "params":{"text":"interim"}
+    }}));
+    std::thread::sleep(std::time::Duration::from_millis(30));
+    json!({"text":params["text"]})
+}
 fn discover(params: &Value) -> Value {
     if let Ok(bytes) = std::fs::read("/state/probe/discover.json") {
         serde_json::from_slice(&bytes).unwrap()
@@ -105,6 +112,25 @@ fn blank() -> Value {
     println!("\n \t\n");
     json!({})
 }
+fn burst(request: &Value) {
+    let count = request["params"]["count"].as_u64().unwrap();
+    let mut output = String::new();
+    for index in 0..count {
+        let notification = json!({
+            "jsonrpc": "2.0",
+            "method": "core.notify",
+            "params": {"name": "burst", "params": {"index": index}}
+        });
+        output.push_str(&notification.to_string());
+        output.push('\n');
+    }
+    let response = json!({"jsonrpc":"2.0", "id":request["id"], "result":count});
+    output.push_str(&response.to_string());
+    output.push('\n');
+    let mut stdout = io::stdout().lock();
+    stdout.write_all(output.as_bytes()).unwrap();
+    stdout.flush().unwrap();
+}
 fn notify() -> Value {
     send(json!({
         "jsonrpc": "2.0",
@@ -281,6 +307,7 @@ fn dispatch(request: &Value, lines: &mut Lines) -> Option<Value> {
         }
         "locked_write" => locked_write(lines),
         "echo" => echo(params),
+        "chat" => chat(params),
         "rpc.discover" => discover(params),
         "env" => environment(),
         "multicall" => multicall(lines),
@@ -304,6 +331,10 @@ fn dispatch(request: &Value, lines: &mut Lines) -> Option<Value> {
         "blank" => blank(),
         "invalid_utf8" => invalid_utf8(),
         "notify" => notify(),
+        "burst" => {
+            burst(request);
+            return None;
+        }
         "serve" => {
             serve(request, lines);
             return None;