### 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.mouse_focus_mask.clear();
								break;
							} else {
								Control *drag_preview = _gui_get_drag_preview();
								if (drag_preview) {
									ERR_PRINT("Don't set a drag preview and return null data. Preview was deleted and drag request ignored.");
									memdelete(drag_preview);
									gui.drag_preview_id = ObjectID();
								}
								gui.dragging = false;
							}
							if (control->data.mouse_filter == Control::MOUSE_FILTER_STOP) {
								break;
							}
						}
						if (ci->is_set_as_top_level()) {
							break;
						}
						ci = ci->get_parent_item();
					}
				}
				gui.drag_attempted = true;
				if (gui.dragging) {
					_propagate_viewport_notification(this, NOTIFICATION_DRAG_BEGIN);
				}
			}
		}
		Control *over = nullptr;
		if (gui.mouse_in_viewport) {
			over = gui_find_control(mpos);