### 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_
	ERR_FAIL_COND(!windows.has(p_window));
	WindowData &wd = windows[p_window];
	switch (p_flag) {
		case WINDOW_FLAG_RESIZE_DISABLED: {
			wd.resizable = !p_enabled;
			_update_window_style(p_window);
		} break;
		case WINDOW_FLAG_BORDERLESS: {
			wd.borderless = p_enabled;
			_update_window_style(p_window);
			_update_window_mouse_passthrough(p_window);
			ShowWindow(wd.hWnd, (wd.no_focus || wd.is_popup) ? SW_SHOWNOACTIVATE : SW_SHOW); 
		} break;
		case WINDOW_FLAG_ALWAYS_ON_TOP: {
			ERR_FAIL_COND_MSG(wd.transient_parent != INVALID_WINDOW_ID && p_enabled, "Transient windows can't become on top");
			wd.always_on_top = p_enabled;
			_update_window_style(p_window);
		} break;
		case WINDOW_FLAG_TRANSPARENT: {
			if (p_enabled) {
				
				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;