Draft: Minor bits of changes to the kcrash code

Hello!

This merge request contains minor changes that I've accumulated over time.

• two new scenarios for tests of which
  • one tests passing of variables to the restarted application
  • the other tests crashing while a second crash is already being handled (this happened to me with Qt)
• removal of the declarations for klauncher, which is unused and gone
• on Windows, we don't need any CoreConfig functionality as it doesn't exist there