### 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)

TRACKMOUSEEVENT tme;
	tme.cbSize = sizeof(TRACKMOUSEEVENT);
	tme.dwFlags = TME_LEAVE;
	tme.hwndTrack = hWnd;
	tme.dwHoverTime = HOVER_DEFAULT;
	TrackMouseEvent(&tme);
}
bool DisplayServerWindows::has_feature(Feature p_feature) const {
	switch (p_feature) {
		case FEATURE_SUBWINDOWS:
		case FEATURE_TOUCHSCREEN:
		case FEATURE_MOUSE:
		case FEATURE_MOUSE_WARP:
		case FEATURE_CLIPBOARD:
		case FEATURE_CURSOR_SHAPE:
		case FEATURE_CUSTOM_CURSOR_SHAPE:
		case FEATURE_IME:
		case FEATURE_WINDOW_TRANSPARENCY:
		case FEATURE_HIDPI:
		case FEATURE_ICON:
		case FEATURE_NATIVE_ICON:
		case FEATURE_SWAP_BUFFERS:
		case FEATURE_KEEP_SCREEN_ON:
		case FEATURE_TEXT_TO_SPEECH:
			return true;
		default:
			return false;
	}
}
String DisplayServerWindows::get_name() const {