Deferred render target initialization
- Asynchronously embed MonadoView into app's activity.
- Deferred/asynchronous creation of android surface (and windows window).
- Window/surface is created inside monado's drawing thread on client session begin.
- Allow to avoid android_looper_poll_until_activity_resumed() during OpenXR instance creation.
- Allows lightweight instance creation (without window/surface creation) if client creates a temporary instance without session start.
- Asynchronous android surface creation will allow to use OpenXR session lifecycle synchronize with android surface creation and foreground status.
- For windows deferred window creation allows to show/hide monado window on client's begin/end of OpenXR session.