[Bug] Notification platform and logged-in users

[fixer]

And one more bug with logged-in users. It's notification platform this time and CreateToastNotifier as an example. Notification platform is tightly bound to shell and logged-in users. So if we try to start process from another user (using API, using runas) and that user isn't logged-in, don't expect notification platform to work.

This issue was found several months ago, it wasn't fixed then. I haven't checked it since, but I suspect it to remain broken for many years to come.