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/project_wizard/content/path/QtProjectWizardContentPathCxxPch.cpp

@@ -57,7 +57,7 @@ bool QtProjectWizardContentPathCxxPch::check()
 		std::shared_ptr<clang::tooling::JSONCompilationDatabase> cdb = utility::loadCDB(cdbPath);
 		if (!cdb)
 		{
-			QMessageBox msgBox;
+			QMessageBox msgBox(m_window);
 			msgBox.setText("Unable to open and read the provided compilation database file.");
 			msgBox.exec();
 			return false;
@@ -67,7 +67,7 @@ bool QtProjectWizardContentPathCxxPch::check()
 		{
 			if (m_settingsCxxPch->getPchInputFilePath().empty())
 			{
-				QMessageBox msgBox;
+				QMessageBox msgBox(m_window);
 				msgBox.setText(
 					"The provided compilation database file uses precompiled headers. If you want "
 					"to make use of "
@@ -89,7 +89,7 @@ bool QtProjectWizardContentPathCxxPch::check()
 		{
 			if (!m_settingsCxxPch->getPchInputFilePath().empty())
 			{
-				QMessageBox msgBox;
+				QMessageBox msgBox(m_window);
 				msgBox.setText(
 					"The provided compilation database file does not use precompiled headers. The "
 					"specified input file at "