### 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)

return tablet_drivers.size();
}
String DisplayServerWindows::tablet_get_driver_name(int p_driver) const {
	if (p_driver < 0 || p_driver >= tablet_drivers.size()) {
		return "";
	} else {
		return tablet_drivers[p_driver];
	}
}
String DisplayServerWindows::tablet_get_current_driver() const {
	return tablet_driver;
}
void DisplayServerWindows::tablet_set_current_driver(const String &p_driver) {
	if (tablet_get_driver_count() == 0) {
		return;
	}
	bool found = false;
	for (int i = 0; i < tablet_get_driver_count(); i++) {
		if (p_driver == tablet_get_driver_name(i)) {
			found = true;
		}
	}
	if (found) {
		_update_tablet_ctx(tablet_driver, p_driver);
		tablet_driver = p_driver;
	} else {
		ERR_PRINT("Unknown tablet driver " + p_driver + ".");
	}
}
DisplayServerWindows::DisplayServerWindows(const String &p_rendering_driver, WindowMode p_mode, VSyncMode p_vsync_mode, uint32_t p_flags, const Vector2i *p_position, const Vector2i &p_resolution, int p_screen, Error &r_error) {