### Godot version

v4.0.beta17.official [c40020513]

### System information

macOS 13.0.1

### Issue description

When a `Control` node is over a `SubViewportContainer` (with a `SubViewport` as a child), both in Full Rect anchors, asking for the get_viewport().get_mouse_position() from a scene inside the `SubViewport` returns (0, 0) as the position of the mouse.

This wasn't happening in at least Beta 15. I was getting the mouse position without any problems before Beta 17. I didn't try Beta 16.

### Steps to reproduce

1. Create a `Control` node
2. Add two children: A `SubViewportContainer` and a `Control` node
3. Put both in Full Rect anchors so the `Control` node (child) is covering the `SubViewportContainer`
4. Ask for the get_viewport().get_mouse_position() from inside a scene of the `SubViewport`

As you can see in this screenshot: asking for the mouse position from inside the `Node2D` script always returns (0, 0).

<img width="1533" alt="SubViewportContainerIssue" src="https://user-images.githubusercontent.com/91340577/217051768-d9c2e8ad-40ca-4c6d-bb98-f6a7c9c6081f.png">

Only If the `Control` (child) mouse filtering is set to _Ignore_ you can get the mouse position. But with that you are losing the mouse inputs from that `Control` node.

You can find the setup of these nodes in the MRP.


### Minimal reproduction project

Run the main scene (control.tscn) and move the mouse around the screen. Look for the print in the Output tab.

[SubViewportMousePositionIssue.zip](https://github.com/godotengine/godot/files/10667894/SubViewportMousePositionIssue.zip)
if (!drag_preview || (c != drag_preview && !drag_preview->is_ancestor_of(c))) {
		return c;
	}
	return nullptr;
}
bool Viewport::_gui_drop(Control *p_at_control, Point2 p_at_pos, bool p_just_check) {
	
	CanvasItem *ci = p_at_control;
	while (ci) {
		Control *control = Object::cast_to<Control>(ci);
		if (control) {
			if (control->can_drop_data(p_at_pos, gui.drag_data)) {
				if (!p_just_check) {
					control->drop_data(p_at_pos, gui.drag_data);
				}
				return true;
			}
			if (control->data.mouse_filter == Control::MOUSE_FILTER_STOP) {
				break;
			}
		}
		p_at_pos = ci->get_transform().xform(p_at_pos);
		if (ci->is_set_as_top_level()) {
			break;
		}
		ci = ci->get_parent_item();
	}
	return false;
}
void Viewport::_gui_input_event(Ref<InputEvent> p_event) {