build: allow to disable language support in cmake

* in addition: add unloadable sourcegroup to visualize, load and save information when loading a project that contains source groups that are not supported by the build

src/lib_gui/qt/project_wizard/content/QtProjectWizardContentJavaStandard.h

@@ -1,6 +1,10 @@
 #ifndef QT_PROJECT_WIZARD_CONTENT_JAVA_STANDARD
 #define QT_PROJECT_WIZARD_CONTENT_JAVA_STANDARD
 
+#include "language_packages.h"
+
+#if BUILD_JAVA_LANGUAGE_PACKAGE
+
 #include "QtProjectWizardContent.h"
 
 class QComboBox;
@@ -28,4 +32,6 @@ private:
 	QComboBox* m_standard;
 };
 
+#endif // BUILD_JAVA_LANGUAGE_PACKAGE
+
 #endif // QT_PROJECT_WIZARD_CONTENT_JAVA_STANDARD