ProjectExplorer: Use FilePath for ProjectNode::{path,directory}

... and let the fallout trickle down a bit.

Change-Id: I1a2f79e281725c4a121cc2fbbc0377e881616ce5
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

src/plugins/projectexplorer/foldernavigationwidget.cpp

@@ -512,7 +512,7 @@ void FolderNavigationWidget::addNewItem()
                                    Utils::filtered(Core::IWizardFactory::allWizardFactories(),
                                                    Utils::equal(&Core::IWizardFactory::kind,
                                                                 Core::IWizardFactory::FileWizard)),
-                                   path.toString());
+                                   path);
 }
 
 void FolderNavigationWidget::editCurrentItem()