### 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 (gui.subwindow_focused) {
		gui.subwindow_focused->push_text_input(p_text);
		return;
	}
	if (gui.key_focus) {
		gui.key_focus->call("set_text", p_text);
	}
}
Viewport::SubWindowResize Viewport::_sub_window_get_resize_margin(Window *p_subwindow, const Point2 &p_point) {
	if (p_subwindow->get_flag(Window::FLAG_BORDERLESS) || p_subwindow->get_flag(Window::FLAG_RESIZE_DISABLED)) {
		return SUB_WINDOW_RESIZE_DISABLED;
	}
	Rect2i r = Rect2i(p_subwindow->get_position(), p_subwindow->get_size());
	int title_height = p_subwindow->get_theme_constant(SNAME("title_height"));
	r.position.y -= title_height;
	r.size.y += title_height;
	if (r.has_point(p_point)) {
		return SUB_WINDOW_RESIZE_DISABLED; 
	}
	int dist_x = p_point.x < r.position.x ? (p_point.x - r.position.x) : (p_point.x > (r.position.x + r.size.x) ? (p_point.x - (r.position.x + r.size.x)) : 0);
	int dist_y = p_point.y < r.position.y ? (p_point.y - r.position.y) : (p_point.y > (r.position.y + r.size.y) ? (p_point.y - (r.position.y + r.size.y)) : 0);
	int limit = p_subwindow->get_theme_constant(SNAME("resize_margin"));
	if (ABS(dist_x) > limit) {
		return SUB_WINDOW_RESIZE_DISABLED;
	}