feat: Column on left, hideable

- columns are hideable (saves to settings)
- image column moved to left
- datamodals can provide resize modes

Signed-off-by: Rachel Powers <508861+Ryex@users.noreply.github.com>

launcher/ui/pages/instance/ExternalResourcesPage.h

@@ -60,6 +60,7 @@ class ExternalResourcesPage : public QMainWindow, public BasePage {
     virtual void viewConfigs();
 
     void ShowContextMenu(const QPoint& pos);
+    void ShowHeaderContextMenu(const QPoint& pos);
 
    protected:
     BaseInstance* m_instance = nullptr;