### 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.
OpenXRHandTrackingExtension *hand_tracking_ext = OpenXRHandTrackingExtension::get_singleton();
	if (hand_tracking_ext && hand_tracking_ext->get_active()) {
		OpenXRInterface::Tracker *tracker = find_tracker(p_path);
		if (tracker && tracker->positional_tracker.is_valid()) {
			XrSpaceLocationFlags location_flags = hand_tracking_ext->get_hand_joint_location_flags(p_hand, XR_HAND_JOINT_PALM_EXT);
			if (location_flags & (XR_SPACE_LOCATION_ORIENTATION_VALID_BIT + XR_SPACE_LOCATION_POSITION_VALID_BIT)) {
				static const XrSpaceLocationFlags all_location_flags = XR_SPACE_LOCATION_ORIENTATION_VALID_BIT + XR_SPACE_LOCATION_POSITION_VALID_BIT + XR_SPACE_LOCATION_ORIENTATION_TRACKED_BIT + XR_SPACE_LOCATION_POSITION_TRACKED_BIT;
				XRPose::TrackingConfidence confidence = XRPose::XR_TRACKING_CONFIDENCE_LOW;
				Transform3D transform;
				Vector3 linear_velocity;
				Vector3 angular_velocity;
				if ((location_flags & all_location_flags) == all_location_flags) {
					
					confidence = XRPose::XR_TRACKING_CONFIDENCE_HIGH;
				}
				if (location_flags & XR_SPACE_LOCATION_ORIENTATION_VALID_BIT) {
					transform.basis = Basis(hand_tracking_ext->get_hand_joint_rotation(p_hand, XR_HAND_JOINT_PALM_EXT));
				}
				if (location_flags & XR_SPACE_LOCATION_POSITION_VALID_BIT) {
					transform.origin = hand_tracking_ext->get_hand_joint_position(p_hand, XR_HAND_JOINT_PALM_EXT);
				}
				XrSpaceVelocityFlags velocity_flags = hand_tracking_ext->get_hand_joint_location_flags(p_hand, XR_HAND_JOINT_PALM_EXT);
				if (velocity_flags & XR_SPACE_VELOCITY_LINEAR_VALID_BIT) {
					linear_velocity = hand_tracking_ext->get_hand_joint_linear_velocity(p_hand, XR_HAND_JOINT_PALM_EXT);
				}