### 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)

Vector2 abs_pos(
							(double(raw->data.mouse.lLastX) - 65536.0 / (nScreenWidth)) * nScreenWidth / 65536.0 + nScreenLeft,
							(double(raw->data.mouse.lLastY) - 65536.0 / (nScreenHeight)) * nScreenHeight / 65536.0 + nScreenTop);
					POINT coords; 
					coords.x = abs_pos.x;
					coords.y = abs_pos.y;
					ScreenToClient(hWnd, &coords);
					mm->set_relative(Vector2(coords.x - old_x, coords.y - old_y));
					old_x = coords.x;
					old_y = coords.y;
				}
				if ((windows[window_id].window_has_focus || windows[window_id].is_popup) && mm->get_relative() != Vector2()) {
					Input::get_singleton()->parse_input_event(mm);
				}
			}
			delete[] lpb;
		} break;
		case WT_CSRCHANGE:
		case WT_PROXIMITY: {
			if ((tablet_get_current_driver() == "wintab") && wintab_available && windows[window_id].wtctx) {
				AXIS pressure;
				if (wintab_WTInfo(WTI_DEVICES + windows[window_id].wtlc.lcDevice, DVC_NPRESSURE, &pressure)) {
					windows[window_id].min_pressure = int(pressure.axMin);
					windows[window_id].max_pressure = int(pressure.axMax);
				}
				AXIS orientation[3];
				if (wintab_WTInfo(WTI_DEVICES + windows[window_id].wtlc.lcDevice, DVC_ORIENTATION, &orientation)) {
					windows[window_id].tilt_supported = orientation[0].axResolution && orientation[1].axResolution;
				}
				return 0;