### 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)

if ((p_new_driver == "wintab") && wintab_available) {
			wintab_WTInfo(WTI_DEFSYSCTX, 0, &wd.wtlc);
			wd.wtlc.lcOptions |= CXO_MESSAGES;
			wd.wtlc.lcPktData = PK_STATUS | PK_NORMAL_PRESSURE | PK_TANGENT_PRESSURE | PK_ORIENTATION;
			wd.wtlc.lcMoveMask = PK_STATUS | PK_NORMAL_PRESSURE | PK_TANGENT_PRESSURE;
			wd.wtlc.lcPktMode = 0;
			wd.wtlc.lcOutOrgX = 0;
			wd.wtlc.lcOutExtX = wd.wtlc.lcInExtX;
			wd.wtlc.lcOutOrgY = 0;
			wd.wtlc.lcOutExtY = -wd.wtlc.lcInExtY;
			wd.wtctx = wintab_WTOpen(wd.hWnd, &wd.wtlc, false);
			if (wd.wtctx) {
				wintab_WTEnable(wd.wtctx, true);
				AXIS pressure;
				if (wintab_WTInfo(WTI_DEVICES + wd.wtlc.lcDevice, DVC_NPRESSURE, &pressure)) {
					wd.min_pressure = int(pressure.axMin);
					wd.max_pressure = int(pressure.axMax);
				}
				AXIS orientation[3];
				if (wintab_WTInfo(WTI_DEVICES + wd.wtlc.lcDevice, DVC_ORIENTATION, &orientation)) {
					wd.tilt_supported = orientation[0].axResolution && orientation[1].axResolution;
				}
				wintab_WTEnable(wd.wtctx, true);
			} else {
				print_verbose("WinTab context creation failed.");
			}
		}
	}
}
DisplayServer::WindowID DisplayServerWindows::_create_window(WindowMode p_mode, VSyncMode p_vsync_mode, uint32_t p_flags, const Rect2i &p_rect) {