### Godot version

v4.0.beta17.mono.official [c40020513]

### System information

Windows 11 22H2

### Issue description

If a focused subwindow is destroyed, DisplayServerWindows may still attempt to send mouse motion events to that window, because `last_focused_window` isn't updated until another window is focused.

```
ERROR: Condition "!windows.has(p_window)" is true. Returning: Point2i()
   at: window_get_position (platform/windows/display_server_windows.cpp:999)
```

### Steps to reproduce

Run the MRP, click some non-Godot application window to focus it, then click the "CLOSE" button in the secondary window. This destroys the window without re-focusing the main window, so hovering the mouse over the main window will produce the error message above.

### Minimal reproduction project

[native_windows_hover.zip](https://github.com/godotengine/godot/files/10573386/native_windows_hover.zip)

windows[window_id].last_pressure_update++;
				} else {
					windows[window_id].last_tilt = Vector2();
					windows[window_id].last_pressure = (wParam & MK_LBUTTON) ? 1.0f : 0.0f;
					windows[window_id].last_pen_inverted = false;
				}
			} else {
				windows[window_id].last_tilt = Vector2();
				windows[window_id].last_pressure = (wParam & MK_LBUTTON) ? 1.0f : 0.0f;
				windows[window_id].last_pen_inverted = false;
			}
			mm->set_pressure(windows[window_id].last_pressure);
			mm->set_tilt(windows[window_id].last_tilt);
			mm->set_pen_inverted(windows[window_id].last_pen_inverted);
			mm->set_button_mask(last_button_state);
			mm->set_position(Vector2(GET_X_LPARAM(lParam), GET_Y_LPARAM(lParam)));
			mm->set_global_position(Vector2(GET_X_LPARAM(lParam), GET_Y_LPARAM(lParam)));
			if (mouse_mode == MOUSE_MODE_CAPTURED) {
				Point2i c(windows[window_id].width / 2, windows[window_id].height / 2);
				old_x = c.x;
				old_y = c.y;
				if (mm->get_position() == c) {
					center = c;
					return 0;
				}
				Point2i ncenter = mm->get_position();
				center = ncenter;
				POINT pos = { (int)c.x, (int)c.y };
				ClientToScreen(windows[window_id].hWnd, &pos);
				SetCursorPos(pos.x, pos.y);