Function onBeforeXRSession

onBeforeXRSession(fn: (args: XRSessionRequestEventArgs) => void): () => void
Add a listener that fires before an XR session is requested. Use this to modify the session init options, e.g. to add optional features like camera-access.
Parameters
- fn: (args: XRSessionRequestEventArgs) => void
  The function to call before the XR session is requested
Returns () => void
A function to remove the listener
Example
```
onBeforeXRSession((args) => {
  args.init.optionalFeatures ??= [];
  args.init.optionalFeatures.push("camera-access");
});
```