### 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)

}
		} break;
		case WM_SYSKEYUP:
		case WM_KEYUP:
			if (windows[window_id].ime_suppress_next_keyup) {
				windows[window_id].ime_suppress_next_keyup = false;
				break;
			}
			[[fallthrough]];
		case WM_SYSKEYDOWN:
		case WM_KEYDOWN: {
			if (windows[window_id].ime_in_progress) {
				break;
			}
			if (wParam == VK_SHIFT) {
				shift_mem = (uMsg == WM_KEYDOWN || uMsg == WM_SYSKEYDOWN);
			}
			if (wParam == VK_CONTROL) {
				control_mem = (uMsg == WM_KEYDOWN || uMsg == WM_SYSKEYDOWN);
			}
			if (wParam == VK_MENU) {
				alt_mem = (uMsg == WM_KEYDOWN || uMsg == WM_SYSKEYDOWN);
				if (lParam & (1 << 24)) {
					gr_mem = alt_mem;
				}
			}
			if (mouse_mode == MOUSE_MODE_CAPTURED) {
				
				if (wParam == VK_F4 && alt_mem && (uMsg == WM_KEYDOWN || uMsg == WM_SYSKEYDOWN)) {
					_send_window_event(windows[window_id], WINDOW_EVENT_CLOSE_REQUEST);