### 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.
XRServer *xr_server = XRServer::get_singleton();
	ERR_FAIL_NULL_V(xr_server, Transform3D());
	Transform3D hmd_transform;
	double world_scale = xr_server->get_world_scale();
	
	hmd_transform.basis = head_transform.basis;
	hmd_transform.origin = head_transform.origin * world_scale;
	return hmd_transform;
}
Transform3D OpenXRInterface::get_transform_for_view(uint32_t p_view, const Transform3D &p_cam_transform) {
	XRServer *xr_server = XRServer::get_singleton();
	ERR_FAIL_NULL_V(xr_server, Transform3D());
	ERR_FAIL_UNSIGNED_INDEX_V_MSG(p_view, get_view_count(), Transform3D(), "View index outside bounds.");
	Transform3D t;
	if (openxr_api && openxr_api->get_view_transform(p_view, t)) {
		
		transform_for_view[p_view] = t;
	} else {
		
		t = transform_for_view[p_view];
	}
	
	double world_scale = xr_server->get_world_scale();
	t.origin *= world_scale;
	return p_cam_transform * xr_server->get_reference_frame() * t;
}
Projection OpenXRInterface::get_projection_for_view(uint32_t p_view, double p_aspect, double p_z_near, double p_z_far) {