### 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.
for (OpenXRExtensionWrapper *extension_wrapper : registered_extension_wrappers) {
		memdelete(extension_wrapper);
	}
	registered_extension_wrappers.clear();
}
Size2 OpenXRAPI::get_recommended_target_size() {
	ERR_FAIL_NULL_V(view_configuration_views, Size2());
	Size2 target_size;
	target_size.width = view_configuration_views[0].recommendedImageRectWidth * render_target_size_multiplier;
	target_size.height = view_configuration_views[0].recommendedImageRectHeight * render_target_size_multiplier;
	return target_size;
}
XRPose::TrackingConfidence OpenXRAPI::get_head_center(Transform3D &r_transform, Vector3 &r_linear_velocity, Vector3 &r_angular_velocity) {
	XrResult result;
	if (!running) {
		return XRPose::XR_TRACKING_CONFIDENCE_NONE;
	}
	
	if (frame_state.predictedDisplayTime == 0) {
		return XRPose::XR_TRACKING_CONFIDENCE_NONE;
	}
	
	XrTime display_time = get_next_frame_time();
	XrSpaceVelocity velocity = {
		XR_TYPE_SPACE_VELOCITY, 
		nullptr, 
		0, 
		{ 0.0, 0.0, 0.0 }, 
		{ 0.0, 0.0, 0.0 } 
	};