### 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.
Basis basis;
	Vector3 origin;
	XRPose::TrackingConfidence confidence = XRPose::XR_TRACKING_CONFIDENCE_NONE;
	const XrPosef &pose = p_location.pose;
	
	if (p_location.locationFlags & XR_SPACE_LOCATION_ORIENTATION_VALID_BIT) {
		Quaternion q(pose.orientation.x, pose.orientation.y, pose.orientation.z, pose.orientation.w);
		r_transform.basis = Basis(q);
		if (p_location.locationFlags & XR_SPACE_LOCATION_ORIENTATION_TRACKED_BIT) {
			
			confidence = XRPose::XR_TRACKING_CONFIDENCE_HIGH;
		} else {
			
			confidence = XRPose::XR_TRACKING_CONFIDENCE_LOW;
		}
	} else {
		r_transform.basis = Basis();
	}
	
	if (p_location.locationFlags & XR_SPACE_LOCATION_POSITION_VALID_BIT) {
		r_transform.origin = Vector3(pose.position.x, pose.position.y, pose.position.z);
		if (!(p_location.locationFlags & XR_SPACE_LOCATION_ORIENTATION_TRACKED_BIT)) {
			
			confidence = XRPose::XR_TRACKING_CONFIDENCE_LOW;
		} else if (confidence == XRPose::XR_TRACKING_CONFIDENCE_NONE) {