### 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)

_THREAD_SAFE_METHOD_
#if defined(VULKAN_ENABLED)
	if (context_vulkan) {
		context_vulkan->set_vsync_mode(p_window, p_vsync_mode);
	}
#endif
#if defined(GLES3_ENABLED)
	if (gl_manager) {
		gl_manager->set_use_vsync(p_window, p_vsync_mode != DisplayServer::VSYNC_DISABLED);
	}
#endif
}
DisplayServer::VSyncMode DisplayServerWindows::window_get_vsync_mode(WindowID p_window) const {
	_THREAD_SAFE_METHOD_
#if defined(VULKAN_ENABLED)
	if (context_vulkan) {
		return context_vulkan->get_vsync_mode(p_window);
	}
#endif
#if defined(GLES3_ENABLED)
	if (gl_manager) {
		return gl_manager->is_using_vsync(p_window) ? DisplayServer::VSYNC_ENABLED : DisplayServer::VSYNC_DISABLED;
	}
#endif
	return DisplayServer::VSYNC_ENABLED;
}
void DisplayServerWindows::set_context(Context p_context) {