### 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)
mb->set_position(pos);
#ifdef DEBUG_ENABLED
			if (EngineDebugger::get_singleton() && gui.mouse_focus) {
				Array arr;
				arr.push_back(gui.mouse_focus->get_path());
				arr.push_back(gui.mouse_focus->get_class());
				EngineDebugger::get_singleton()->send_message("scene:click_ctrl", arr);
			}
#endif
			if (mb->get_button_index() == MouseButton::LEFT) { 
				CanvasItem *ci = gui.mouse_focus;
				while (ci) {
					Control *control = Object::cast_to<Control>(ci);
					if (control) {
						if (control->get_focus_mode() != Control::FOCUS_NONE) {
							if (control != gui.key_focus) {
								control->grab_focus();
							}
							break;
						}
						if (control->data.mouse_filter == Control::MOUSE_FILTER_STOP) {
							break;
						}
					}
					if (ci->is_set_as_top_level()) {
						break;
					}
					ci = ci->get_parent_item();
				}
			}