### 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(p_window == p_parent);
	ERR_FAIL_COND(!windows.has(p_window));
	WindowData &wd_window = windows[p_window];
	ERR_FAIL_COND(wd_window.transient_parent == p_parent);
	ERR_FAIL_COND_MSG(wd_window.always_on_top, "Windows with the 'on top' can't become transient.");
	if (p_parent == INVALID_WINDOW_ID) {
		
		ERR_FAIL_COND(wd_window.transient_parent == INVALID_WINDOW_ID);
		ERR_FAIL_COND(!windows.has(wd_window.transient_parent));
		WindowData &wd_parent = windows[wd_window.transient_parent];
		wd_window.transient_parent = INVALID_WINDOW_ID;
		wd_parent.transient_children.erase(p_window);
		if (wd_window.exclusive) {
			SetWindowLongPtr(wd_window.hWnd, GWLP_HWNDPARENT, (LONG_PTR) nullptr);
		}
	} else {
		ERR_FAIL_COND(!windows.has(p_parent));
		ERR_FAIL_COND_MSG(wd_window.transient_parent != INVALID_WINDOW_ID, "Window already has a transient parent");
		WindowData &wd_parent = windows[p_parent];
		wd_window.transient_parent = p_parent;
		wd_parent.transient_children.insert(p_window);
		if (wd_window.exclusive) {
			SetWindowLongPtr(wd_window.hWnd, GWLP_HWNDPARENT, (LONG_PTR)wd_parent.hWnd);
		}
	}
}
void DisplayServerWindows::window_set_max_size(const Size2i p_size, WindowID p_window) {