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/src/routing.rs

@@ -220,6 +220,30 @@ impl Host {
             return;
         }
         if let Some(method) = v["method"].as_str() {
+            if method == "core.notify" {
+                // Deliver progress before a following response removes its destination.
+                let params = v.get("params").cloned().unwrap_or(json!({}));
+                let result = if !params.is_object() {
+                    Err(error(-32602, "params must be an object"))
+                } else if let Some(name) = params["name"].as_str() {
+                    self.notify(
+                        pid,
+                        name,
+                        params.get("params").cloned().unwrap_or(json!({})),
+                    );
+                    Ok(Value::Null)
+                } else {
+                    Err(error(-32602, "name must be a string"))
+                };
+                if let Some(id) = v.get("id") {
+                    let response = match result {
+                        Ok(result) => json!({"jsonrpc":"2.0", "id":id, "result":result}),
+                        Err(error) => json!({"jsonrpc":"2.0", "id":id, "error":error}),
+                    };
+                    self.send(pid, response);
+                }
+                return;
+            }
             let h = self.clone();
             let caller = pid.to_string();
             let method = method.to_string();