### 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)

ERR_PRINT("invalid utf16 surrogate input");
							break; 
						}
						unicode = (prev_wck << 10UL) + unicode - ((0xd800 << 10UL) + 0xdc00 - 0x10000);
						prev_wck = 0;
					} else {
						prev_wck = 0;
					}
					k->set_unicode(fix_unicode(unicode));
				}
				if (k->get_unicode() && gr_mem) {
					k->set_alt_pressed(false);
					k->set_ctrl_pressed(false);
				}
				k->set_echo((ke.uMsg == WM_KEYDOWN && (ke.lParam & (1 << 30))));
				Input::get_singleton()->parse_input_event(k);
			} break;
		}
	}
	key_event_pos = 0;
}
void DisplayServerWindows::_update_tablet_ctx(const String &p_old_driver, const String &p_new_driver) {
	for (KeyValue<WindowID, WindowData> &E : windows) {
		WindowData &wd = E.value;
		wd.block_mm = false;
		if ((p_old_driver == "wintab") && wintab_available && wd.wtctx) {
			wintab_WTEnable(wd.wtctx, false);
			wintab_WTClose(wd.wtctx);
			wd.wtctx = 0;
		}