### 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)

EnumScreenData *data = (EnumScreenData *)dwData;
	if (data->monitor == hMonitor) {
		data->screen = data->count;
	}
	data->count++;
	return TRUE;
}
static BOOL CALLBACK _MonitorEnumProcCount(HMONITOR hMonitor, HDC hdcMonitor, LPRECT lprcMonitor, LPARAM dwData) {
	int *data = (int *)dwData;
	(*data)++;
	return TRUE;
}
int DisplayServerWindows::get_screen_count() const {
	_THREAD_SAFE_METHOD_
	int data = 0;
	EnumDisplayMonitors(nullptr, nullptr, _MonitorEnumProcCount, (LPARAM)&data);
	return data;
}
int DisplayServerWindows::get_primary_screen() const {
	EnumScreenData data = { 0, 0, 0 };
	EnumDisplayMonitors(nullptr, nullptr, _MonitorEnumProcPrim, (LPARAM)&data);
	return data.screen;
}
typedef struct {
	int count;
	int screen;
	Point2 pos;
} EnumPosData;
static BOOL CALLBACK _MonitorEnumProcPos(HMONITOR hMonitor, HDC hdcMonitor, LPRECT lprcMonitor, LPARAM dwData) {