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/settings/source_group/component/java/SourceGroupSettingsWithSourceExtensionsJava.h

@@ -1,6 +1,10 @@
 #ifndef SOURCE_GROUP_SETTINGS_WITH_SOURCE_EXTENSIONS_JAVA_H
 #define SOURCE_GROUP_SETTINGS_WITH_SOURCE_EXTENSIONS_JAVA_H
 
+#include "language_packages.h"
+
+#if BUILD_JAVA_LANGUAGE_PACKAGE
+
 #include "SourceGroupSettingsWithSourceExtensions.h"
 
 class SourceGroupSettingsWithSourceExtensionsJava
@@ -13,4 +17,6 @@ private:
 	}
 };
 
+#endif // BUILD_JAVA_LANGUAGE_PACKAGE
+
 #endif // SOURCE_GROUP_SETTINGS_WITH_SOURCE_EXTENSIONS_JAVA_H