ProjectExplorer: Remove Project manager parameter from some constructors

Can be done generically when creating projects. The only wart is
the use from BaseQmakeProjectWizardDialog::writeUserFile.

Change-Id: Ie98c9f88ec142e82443e204a0075e3ae9e163752
Reviewed-by: Tobias Hunger <tobias.hunger@qt.io>

src/plugins/genericprojectmanager/genericproject.h

@@ -49,7 +49,7 @@ class GenericProject : public ProjectExplorer::Project
     Q_OBJECT
 
 public:
-    GenericProject(Manager *manager, const QString &filename);
+    explicit GenericProject(const QString &filename);
     ~GenericProject() override;
 
     QString filesFileName() const;