GitLab

* Get rid of CppModelManagerHelper.
  Now we simply use CppModelManager::projectInfo(someProject).isValid() to
  test whether a project is loaded.

* Copy project data to temporary dir before opening the projects.
  This avoids creating *.user files in the Qt Creator source tree and
  annoying pop ups on test start.

Change-Id: I1a57441ca2099beb6bb96cf620390d669fb47601
Reviewed-by: Christian Stenger <christian.stenger@theqtcompany.com>