### Godot version

4.2.dev 80de898d721f952dac0b102d48bb73d6b02ee1e8

### System information

OpenXR

### Issue description

The Godot 3 OpenXR plugin supported obtaining boundary/guardian information in order to obtain play space logic. While we do have a function in the `XRInterface` in Godot 4 that is supposed to retrieve this information (`get_play_area`) it is not implemented on the Godot 4 `OpenXRInterface`.

This logic needs to be ported.

### Steps to reproduce

Call `get_play_area`, be amazed by it not returning data :P

### Minimal reproduction project

Any XR project.
return render_target_size_multiplier;
}
void OpenXRAPI::set_render_target_size_multiplier(double multiplier) {
	render_target_size_multiplier = multiplier;
}
bool OpenXRAPI::is_foveation_supported() const {
	OpenXRFBFoveationExtension *fov_ext = OpenXRFBFoveationExtension::get_singleton();
	return fov_ext != nullptr && fov_ext->is_enabled();
}
int OpenXRAPI::get_foveation_level() const {
	OpenXRFBFoveationExtension *fov_ext = OpenXRFBFoveationExtension::get_singleton();
	if (fov_ext != nullptr && fov_ext->is_enabled()) {
		switch (fov_ext->get_foveation_level()) {
			case XR_FOVEATION_LEVEL_NONE_FB:
				return 0;
			case XR_FOVEATION_LEVEL_LOW_FB:
				return 1;
			case XR_FOVEATION_LEVEL_MEDIUM_FB:
				return 2;
			case XR_FOVEATION_LEVEL_HIGH_FB:
				return 3;
			default:
				return 0;
		}
	}
	return 0;
}
void OpenXRAPI::set_foveation_level(int p_foveation_level) {