### 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)

wd.no_focus = true;
	}
	if (p_flags & WINDOW_FLAG_MOUSE_PASSTHROUGH_BIT) {
		wd.mpass = true;
	}
	if (p_flags & WINDOW_FLAG_POPUP_BIT) {
		wd.is_popup = true;
	}
	if (p_flags & WINDOW_FLAG_TRANSPARENT_BIT) {
		DWM_BLURBEHIND bb;
		ZeroMemory(&bb, sizeof(bb));
		HRGN hRgn = CreateRectRgn(0, 0, -1, -1);
		bb.dwFlags = DWM_BB_ENABLE | DWM_BB_BLURREGION;
		bb.hRgnBlur = hRgn;
		bb.fEnable = TRUE;
		DwmEnableBlurBehindWindow(wd.hWnd, &bb);
		wd.layered_window = true;
	}
	
	HICON mainwindow_icon = (HICON)SendMessage(windows[MAIN_WINDOW_ID].hWnd, WM_GETICON, ICON_SMALL, 0);
	if (mainwindow_icon) {
		SendMessage(windows[window_id].hWnd, WM_SETICON, ICON_SMALL, (LPARAM)mainwindow_icon);
	}
	mainwindow_icon = (HICON)SendMessage(windows[MAIN_WINDOW_ID].hWnd, WM_GETICON, ICON_BIG, 0);
	if (mainwindow_icon) {
		SendMessage(windows[window_id].hWnd, WM_SETICON, ICON_BIG, (LPARAM)mainwindow_icon);
	}
	return window_id;
}
void DisplayServerWindows::show_window(WindowID p_id) {