Core: Add LoggingView support

Add a way to inspect QC internal loggings. This is basically
useful for inspecting issues while running QC and facing them
without the need to restart and set appropriate logging rules.

Change-Id: Ic647ba1abfb2611c4e4e99a375413d399c71886d
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Alessandro Portale <alessandro.portale@qt.io>

src/plugins/coreplugin/mainwindow.h

@@ -188,6 +188,7 @@ private:
     QAction *m_saveAllAction = nullptr;
     QAction *m_exitAction = nullptr;
     QAction *m_optionsAction = nullptr;
+    QAction *m_loggerAction = nullptr;
     QAction *m_toggleLeftSideBarAction = nullptr;
     QAction *m_toggleRightSideBarAction = nullptr;
     QAction *m_cycleModeSelectorStyleAction = nullptr;