### 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 {
			rect.left = 0;
			rect.right = wd.width;
			rect.top = 0;
			rect.bottom = wd.height;
			wd.pre_fs_valid = true;
		}
		_update_window_style(p_window, false);
		MoveWindow(wd.hWnd, rect.left, rect.top, rect.right - rect.left, rect.bottom - rect.top, TRUE);
		if (restore_mouse_trails > 1) {
			SystemParametersInfoA(SPI_SETMOUSETRAILS, restore_mouse_trails, 0, 0);
			restore_mouse_trails = 0;
		}
	} else if (p_mode == WINDOW_MODE_WINDOWED) {
		ShowWindow(wd.hWnd, SW_RESTORE);
		wd.maximized = false;
		wd.minimized = false;
	}
	if (p_mode == WINDOW_MODE_MAXIMIZED) {
		ShowWindow(wd.hWnd, SW_MAXIMIZE);
		wd.maximized = true;
		wd.minimized = false;
	}
	if (p_mode == WINDOW_MODE_MINIMIZED) {
		ShowWindow(wd.hWnd, SW_MINIMIZE);
		wd.maximized = false;
		wd.minimized = true;
	}
	if (p_mode == WINDOW_MODE_EXCLUSIVE_FULLSCREEN) {
		wd.multiwindow_fs = false;