Impl sceSystemServiceLoadExec (#3647)

* Add support for restarting the emulator with new configurations

- Implement `Restart` function in `Emulator` to enable process relaunch with updated parameters.
- Modify `sceSystemServiceLoadExec` to use the restart functionality.

* Add logging for emulator restart and system service load execution

* Add IPC emulator PID output command

Impl `PID` output command to return the emulator process ID
- required for launches supporting emulator restart

* Add log file append mode support (used after restarting to keep the same log file)

* Keep game root between restarts

* add --wait-for-debugger option flag

* add --wait-for-pid flag

used for sync between parent & child process during restart

* impl restart via ipc

* fix override game root

* add qt flags to allow restart

src/qt_gui/main_window.cpp

@@ -1225,12 +1225,12 @@ void MainWindow::StartEmulator(std::filesystem::path path) {
     isGameRunning = true;
 #ifdef __APPLE__
     // SDL on macOS requires main thread.
-    Core::Emulator emulator;
-    emulator.Run(path);
+    Core::Emulator* emulator = Common::Singleton<Core::Emulator>::Instance();
+    emulator->Run(path);
 #else
     std::thread emulator_thread([=] {
-        Core::Emulator emulator;
-        emulator.Run(path);
+        Core::Emulator* emulator = Common::Singleton<Core::Emulator>::Instance();
+        emulator->Run(path);
     });
     emulator_thread.detach();
 #endif