### 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_
	Ref<FileAccess> f = FileAccess::open(p_filename, FileAccess::READ);
	ERR_FAIL_COND_MSG(f.is_null(), "Cannot open file with icon '" + p_filename + "'.");
	ICONDIR *icon_dir = (ICONDIR *)memalloc(sizeof(ICONDIR));
	int pos = 0;
	icon_dir->idReserved = f->get_32();
	pos += sizeof(WORD);
	f->seek(pos);
	icon_dir->idType = f->get_32();
	pos += sizeof(WORD);
	f->seek(pos);
	ERR_FAIL_COND_MSG(icon_dir->idType != 1, "Invalid icon file format!");
	icon_dir->idCount = f->get_32();
	pos += sizeof(WORD);
	f->seek(pos);
	icon_dir = (ICONDIR *)memrealloc(icon_dir, sizeof(ICONDIR) - sizeof(ICONDIRENTRY) + icon_dir->idCount * sizeof(ICONDIRENTRY));
	f->get_buffer((uint8_t *)&icon_dir->idEntries[0], icon_dir->idCount * sizeof(ICONDIRENTRY));
	int small_icon_index = -1; 
	int small_icon_cc = 0;
	int big_icon_index = -1; 
	int big_icon_width = 16;
	int big_icon_cc = 0;
	for (int i = 0; i < icon_dir->idCount; i++) {
		int colors = (icon_dir->idEntries[i].bColorCount == 0) ? 32768 : icon_dir->idEntries[i].bColorCount;
		int width = (icon_dir->idEntries[i].bWidth == 0) ? 256 : icon_dir->idEntries[i].bWidth;
		if (width == 16) {
			if (colors >= small_icon_cc) {
				small_icon_index = i;
				small_icon_cc = colors;
			}