Add COM initializition to Windows template (#54881)

Plugins, and the library, should be able to use COM without special
setup. This adds COM initialization to the runner template so that it's
available for any code on the main thread.

packages/flutter_tools/templates/app/windows.tmpl/runner/main.cpp

@@ -16,6 +16,9 @@ int APIENTRY wWinMain(_In_ HINSTANCE instance,
     ::AllocConsole();
   }
 
+  // Initialize COM, so that it is available for use in the library and/or plugins.
+  ::CoInitializeEx(nullptr, COINIT_APARTMENTTHREADED);
+
   RunLoop run_loop;
 
   flutter::DartProject project(L"data");
@@ -29,5 +32,6 @@ int APIENTRY wWinMain(_In_ HINSTANCE instance,
 
   run_loop.Run();
 
+  ::CoUninitialize();
   return EXIT_SUCCESS;
 }