### 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)

#include "display_server_windows.h"
#include "core/io/marshalls.h"
#include "core/math/geometry_2d.h"
#include "main/main.h"
#include "os_windows.h"
#include "scene/resources/texture.h"
#include <avrt.h>
#include <dwmapi.h>
#ifndef DWMWA_USE_IMMERSIVE_DARK_MODE
#define DWMWA_USE_IMMERSIVE_DARK_MODE 20
#endif
#if defined(GLES3_ENABLED)
#include "drivers/gles3/rasterizer_gles3.h"
#endif
#if defined(__GNUC__)
#define GetProcAddress (void *)GetProcAddress
#endif
static String format_error_message(DWORD id) {
	LPWSTR messageBuffer = nullptr;
	size_t size = FormatMessageW(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
			nullptr, id, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), (LPWSTR)&messageBuffer, 0, nullptr);
	String msg = "Error " + itos(id) + ": " + String::utf16((const char16_t *)messageBuffer, size);
	LocalFree(messageBuffer);
	return msg;
}
static void track_mouse_leave_event(HWND hWnd) {