Define shortcuts to launch the client with either Vulkan or OpenGL graphics backend, which can be accessed by long-pressing the app icon on the home screen. This feature is available for Android 7.1 and newer.
Restarting the client previously did not work, as the `shell_execute` function on Android uses `fork` which is not supported.
Now, the client is restarted by using an Android intent to restart the main activity. This is triggered by sending a user-defined message from the native code to the SDL main activity thread.
SDL automatically loads the libraries specified in the array returned by the `getLibraries` method, so loading it manually is unnecessary. SDL also has additional error handling to quit the app with an appropriate error message popup if the library could not be loaded, which was not handled previously.
