feat: add --safe-mode command line option (#4985)

This ensures the settings button isn't hidden, and disables plugins from being loaded to make sure the user can always recover from messing things up

src/common/Args.hpp

@@ -26,6 +26,7 @@ public:
     bool dontLoadMainWindow{};
     std::optional<WindowLayout> customChannelLayout;
     bool verbose{};
+    bool safeMode{};
 
 private:
     void applyCustomChannelLayout(const QString &argValue);