### 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)

} else {
						mb->set_button_index(MouseButton::MB_XBUTTON2);
					}
				} break;
				case WM_XBUTTONDBLCLK: {
					mb->set_pressed(true);
					if (HIWORD(wParam) == XBUTTON1) {
						mb->set_button_index(MouseButton::MB_XBUTTON1);
					} else {
						mb->set_button_index(MouseButton::MB_XBUTTON2);
					}
					mb->set_double_click(true);
				} break;
				default: {
					return 0;
				}
			}
			mb->set_ctrl_pressed((wParam & MK_CONTROL) != 0);
			mb->set_shift_pressed((wParam & MK_SHIFT) != 0);
			mb->set_alt_pressed(alt_mem);
			
			if (mb->is_pressed()) {
				last_button_state.set_flag(mouse_button_to_mask(mb->get_button_index()));
			} else {
				last_button_state.clear_flag(mouse_button_to_mask(mb->get_button_index()));
			}
			mb->set_button_mask(last_button_state);
			mb->set_position(Vector2(GET_X_LPARAM(lParam), GET_Y_LPARAM(lParam)));
			if (mouse_mode == MOUSE_MODE_CAPTURED && !use_raw_input) {
				mb->set_position(Vector2(old_x, old_y));