### 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)

}
			}
			[[fallthrough]];
		}
		case WM_CHAR: {
			ERR_BREAK(key_event_pos >= KEY_EVENT_BUFFER_SIZE);
			
			KeyEvent ke;
			ke.shift = (wParam != VK_SHIFT) ? shift_mem : false;
			ke.alt = (!(wParam == VK_MENU && (uMsg == WM_KEYDOWN || uMsg == WM_SYSKEYDOWN))) ? alt_mem : false;
			ke.control = (wParam != VK_CONTROL) ? control_mem : false;
			ke.meta = meta_mem;
			ke.uMsg = uMsg;
			ke.window_id = window_id;
			if (ke.uMsg == WM_SYSKEYDOWN) {
				ke.uMsg = WM_KEYDOWN;
			}
			if (ke.uMsg == WM_SYSKEYUP) {
				ke.uMsg = WM_KEYUP;
			}
			ke.wParam = wParam;
			ke.lParam = lParam;
			key_event_buffer[key_event_pos++] = ke;
		} break;
		case WM_IME_COMPOSITION: {
			CANDIDATEFORM cf;
			cf.dwIndex = 0;
			cf.dwStyle = CFS_CANDIDATEPOS;
			cf.ptCurrentPos.x = windows[window_id].im_position.x;
			cf.ptCurrentPos.y = windows[window_id].im_position.y;