### 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)

FreeLibrary(Shcore);
			}
			Shcore = (HMODULE)INVALID_HANDLE_VALUE;
		}
	}
	UINT x = 0, y = 0;
	if (hmon && (Shcore != (HMODULE)INVALID_HANDLE_VALUE)) {
		HRESULT hr = getDPIForMonitor(hmon, dpiType , &x, &y);
		if (SUCCEEDED(hr) && (x > 0) && (y > 0)) {
			dpiX = (int)x;
			dpiY = (int)y;
		}
	} else {
		static int overallX = 0, overallY = 0;
		if (overallX <= 0 || overallY <= 0) {
			HDC hdc = GetDC(nullptr);
			if (hdc) {
				overallX = GetDeviceCaps(hdc, LOGPIXELSX);
				overallY = GetDeviceCaps(hdc, LOGPIXELSY);
				ReleaseDC(nullptr, hdc);
			}
		}
		if (overallX > 0 && overallY > 0) {
			dpiX = overallX;
			dpiY = overallY;
		}
	}
	return (dpiX + dpiY) / 2;
}
static BOOL CALLBACK _MonitorEnumProcDpi(HMONITOR hMonitor, HDC hdcMonitor, LPRECT lprcMonitor, LPARAM dwData) {