(TutoEditorQml): fix the crash when the application is launched

What does this MR do?

The startService in onServiceCreated() is removed. AppManager base class has been updated to automatically start the services when they are added (if startServices() has been called once).

How to test it?

Lauch TutoEditorQml. Try to write on both editors.

Associated Issues/Merge Requests

• Issues
  • Fixes #347 (closed)