### 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)
gui.subwindow_drag = SUB_WINDOW_DRAG_DISABLED;
		gui.subwindow_focused->_event_callback(DisplayServer::WINDOW_EVENT_FOCUS_OUT);
		if (parent_visible) {
			new_focused_window = parent_visible;
		} else {
			new_focused_window = Object::cast_to<Window>(this);
		}
		if (new_focused_window) {
			int new_focused_index = _sub_window_find(new_focused_window);
			if (new_focused_index != -1) {
				gui.subwindow_focused = new_focused_window;
			} else {
				gui.subwindow_focused = nullptr;
			}
			new_focused_window->_event_callback(DisplayServer::WINDOW_EVENT_FOCUS_IN);
		} else {
			gui.subwindow_focused = nullptr;
		}
	}
	RenderingServer::get_singleton()->viewport_set_parent_viewport(p_window->viewport, p_window->parent ? p_window->parent->viewport : RID());
}
int Viewport::_sub_window_find(Window *p_window) {
	for (int i = 0; i < gui.sub_windows.size(); i++) {
		if (gui.sub_windows[i].window == p_window) {
			return i;
		}
	}
	return -1;
}
void Viewport::_notification(int p_what) {