Removed multiple dialog steps in Source Group setup (issue #723) (#913)

* removed QtSourceGroupWizard, QtSourceGroupWizardPage and context types
* removed isInForm flag of QtProjectWizardContent
* added check of empty source paths
* set project window as parent for message boxes, so they don't get hidden behind main window
* fixed issues when removing and duplicating source groups
* updated project setup tests to no steps

src/lib_gui/qt/element/button/QtHelpButton.h

@@ -11,11 +11,14 @@ class QtHelpButton: public QtIconButton
 public:
 	QtHelpButton(const QtHelpButtonInfo& info, QWidget* parent = nullptr);
 
+	void setMessageBoxParent(QWidget* messageBoxParent);
+
 private slots:
 	void handleHelpPress();
 
 private:
 	QtHelpButtonInfo m_info;
+	QWidget* m_messageBoxParent = nullptr;
 };
 
 #endif	  // QT_HELP_BUTTON_H