Fix gui_plugin_interface.h m_logger member and ltsmultimonitor_export.h alias

- Add m_logger member to GuiPluginInterface private section
- Create ltsmultimonitor_export.h as alias for lts_multi_monitor_export.h

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

qt6-after/qt6-migrated-legatus/Lts/Common/PluginInterfaces/gui_plugin_interface.h

@@ -136,6 +136,7 @@ class Interface
     QFlags<LtsAppDescriptor::PluginInfo::Flag> m_flags;
     QStringList m_options;
     LtsAppDescriptor::App m_appId;
+    NGL::INGLLogger& m_logger;
 };
 
 } // namespace GuiPluginBase