### 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)

}
			if (bHandled) {
				CloseTouchInputHandle((HTOUCHINPUT)lParam);
				return 0;
			}
		} break;
		case WM_DEVICECHANGE: {
			joypad->probe_joypads();
		} break;
		case WM_DESTROY: {
			Input::get_singleton()->flush_buffered_events();
		} break;
		case WM_SETCURSOR: {
			if (LOWORD(lParam) == HTCLIENT) {
				if (windows[window_id].window_has_focus && (mouse_mode == MOUSE_MODE_HIDDEN || mouse_mode == MOUSE_MODE_CAPTURED || mouse_mode == MOUSE_MODE_CONFINED_HIDDEN)) {
					
					if (hCursor == nullptr) {
						hCursor = SetCursor(nullptr);
					} else {
						SetCursor(nullptr);
					}
				} else {
					if (hCursor != nullptr) {
						CursorShape c = cursor_shape;
						cursor_shape = CURSOR_MAX;
						cursor_set_shape(c);
						hCursor = nullptr;
					}
				}