### 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)

image = texture->get_image();
		}
		if (!image.is_valid() && atlas_texture.is_valid()) {
			texture = atlas_texture->get_atlas();
			atlas_rect.size.width = texture->get_width();
			atlas_rect.size.height = texture->get_height();
			atlas_rect.position.x = atlas_texture->get_region().position.x;
			atlas_rect.position.y = atlas_texture->get_region().position.y;
			texture_size.width = atlas_texture->get_region().size.x;
			texture_size.height = atlas_texture->get_region().size.y;
		} else if (image.is_valid()) {
			texture_size.width = texture->get_width();
			texture_size.height = texture->get_height();
		}
		ERR_FAIL_COND(!texture.is_valid());
		ERR_FAIL_COND(p_hotspot.x < 0 || p_hotspot.y < 0);
		ERR_FAIL_COND(texture_size.width > 256 || texture_size.height > 256);
		ERR_FAIL_COND(p_hotspot.x > texture_size.width || p_hotspot.y > texture_size.height);
		image = texture->get_image();
		ERR_FAIL_COND(!image.is_valid());
		UINT image_size = texture_size.width * texture_size.height;
		
		COLORREF *buffer = nullptr;
		BITMAPV5HEADER bi;
		ZeroMemory(&bi, sizeof(bi));
		bi.bV5Size = sizeof(bi);
		bi.bV5Width = texture_size.width;
		bi.bV5Height = -texture_size.height;
		bi.bV5Planes = 1;
		bi.bV5BitCount = 32;