🐛 fix(async_executor): implement cooperative cancellation

lsp-server/test/test_provider/json_provider_coverage_test.cppm

@@ -49,7 +49,7 @@ namespace lsp::test::provider
 
         struct ProviderEnv
         {
-            scheduler::AsyncExecutor scheduler{ 1 };
+            scheduler::async_executor::AsyncExecutor scheduler{ 1 };
             manager::ManagerHub hub{};
             core::RequestDispatcher dispatcher{};
 
@@ -1225,7 +1225,7 @@ namespace lsp::test::provider
         auto code_action_tree = env.hub.parser().GetTree(code_action_uri);
         auto code_action_diagnostics = BuildDiagnosticsFromSyntaxErrors(code_action_tree, code_action_content);
 
-        env.scheduler.Submit("json_cancel_me", []() -> std::optional<std::string> {
+        env.scheduler.Submit("json_cancel_me", [](std::stop_token) -> std::optional<std::string> {
             std::this_thread::sleep_for(std::chrono::milliseconds(200));
             return std::string("done");
         });