Runner: fix startup task state setting for MSIX (#1181)

src/common/winstore.h

@@ -1,3 +1,15 @@
 #pragma once
 
-bool running_as_packaged();
+#include <future>
+
+#include <winrt/Windows.ApplicationModel.h>
+
+
+namespace winstore
+{
+    using winrt::Windows::ApplicationModel::StartupTaskState;
+
+    bool running_as_packaged();
+    std::future<void> switch_startup_task_state_async(const bool enabled);
+    std::future<StartupTaskState> get_startup_task_status_async();
+}