### 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()) {
		return hand_tracking_ext->get_hand_joint_rotation(OpenXRHandTrackingExtension::HandTrackedHands(p_hand), XrHandJointEXT(p_joint));
	}
	return Quaternion();
}
Vector3 OpenXRInterface::get_hand_joint_position(Hand p_hand, HandJoints p_joint) const {
	OpenXRHandTrackingExtension *hand_tracking_ext = OpenXRHandTrackingExtension::get_singleton();
	if (hand_tracking_ext && hand_tracking_ext->get_active()) {
		return hand_tracking_ext->get_hand_joint_position(OpenXRHandTrackingExtension::HandTrackedHands(p_hand), XrHandJointEXT(p_joint));
	}
	return Vector3();
}
float OpenXRInterface::get_hand_joint_radius(Hand p_hand, HandJoints p_joint) const {
	OpenXRHandTrackingExtension *hand_tracking_ext = OpenXRHandTrackingExtension::get_singleton();
	if (hand_tracking_ext && hand_tracking_ext->get_active()) {
		return hand_tracking_ext->get_hand_joint_radius(OpenXRHandTrackingExtension::HandTrackedHands(p_hand), XrHandJointEXT(p_joint));
	}
	return 0.0;
}
Vector3 OpenXRInterface::get_hand_joint_linear_velocity(Hand p_hand, HandJoints p_joint) const {
	OpenXRHandTrackingExtension *hand_tracking_ext = OpenXRHandTrackingExtension::get_singleton();
	if (hand_tracking_ext && hand_tracking_ext->get_active()) {
		return hand_tracking_ext->get_hand_joint_linear_velocity(OpenXRHandTrackingExtension::HandTrackedHands(p_hand), XrHandJointEXT(p_joint));
	}
	return Vector3();
}
Vector3 OpenXRInterface::get_hand_joint_angular_velocity(Hand p_hand, HandJoints p_joint) const {