Notify user when ASCOM is not installed

[Stefan B]

Currently when installing N.I.N.A. there is no validation check that the ASCOM Platform is already installed. Without it the application cannot run and won't start up.

There should be some way to tell a user during setup or during application start that this is required.

Preferred method for now: Add a check to the installer that this dependency has to be installed first.

[Stefan B]

Application will be able to start without ascom in the next build