### 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)

}
			return 1;
		} break;
		case WM_PAINT: {
			Main::force_redraw();
		} break;
		case WM_SETTINGCHANGE: {
			if (lParam && CompareStringOrdinal(reinterpret_cast<LPCWCH>(lParam), -1, L"ImmersiveColorSet", -1, true) == CSTR_EQUAL) {
				if (is_dark_mode_supported() && dark_title_available) {
					BOOL value = is_dark_mode();
					::DwmSetWindowAttribute(windows[window_id].hWnd, DWMWA_USE_IMMERSIVE_DARK_MODE, &value, sizeof(value));
				}
			}
		} break;
		case WM_THEMECHANGED: {
			if (is_dark_mode_supported() && dark_title_available) {
				BOOL value = is_dark_mode();
				::DwmSetWindowAttribute(windows[window_id].hWnd, DWMWA_USE_IMMERSIVE_DARK_MODE, &value, sizeof(value));
			}
		} break;
		case WM_SYSCOMMAND: 
		{
			switch (wParam) 
			{
				case SC_SCREENSAVE: 
				case SC_MONITORPOWER: 
					return 0; 
				case SC_KEYMENU:
					if ((lParam >> 16) <= 0) {
						return 0;