### 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.
ERR_FAIL_COND_V(session == XR_NULL_HANDLE, XRPose::XR_TRACKING_CONFIDENCE_NONE);
	Action *action = action_owner.get_or_null(p_action);
	ERR_FAIL_NULL_V(action, XRPose::XR_TRACKING_CONFIDENCE_NONE);
	Tracker *tracker = tracker_owner.get_or_null(p_tracker);
	ERR_FAIL_NULL_V(tracker, XRPose::XR_TRACKING_CONFIDENCE_NONE);
	if (!running) {
		return XRPose::XR_TRACKING_CONFIDENCE_NONE;
	}
	ERR_FAIL_COND_V(action->action_type != XR_ACTION_TYPE_POSE_INPUT, XRPose::XR_TRACKING_CONFIDENCE_NONE);
	
	uint64_t index = 0xFFFFFFFF;