Expose reference from <Application /> component #309

Hi 👋 We’re using PlayCanvas with React in a Next.js app, where the UI and the game scene are fully separated at the top level to avoid unnecessary re-renders.

...
return (
  <ManagersProvider>
    {/* UI */}
    <GameInterface />

    {/* Game */}
    <div className='game-scene'>
      <Application {/* ref={appRef} */} {...gameApplicationOptions}>
        <GameNext />
        <Map />
      </Application>
    </div>
  </ManagersProvider>
);

In our case, we sometimes need access to the "app" object before the scene is rendered, for example to run some preprocessing logic like asset/texture loading. Right now, this is only possible via the "useApp" hook.

If it were possible to get a ref directly from the component, it would simplify these preprocessing steps quite a bit and make the architecture cleaner.

Happy to help or discuss further if this sounds useful,