### 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)

HMODULE user32_lib = LoadLibraryW(L"user32.dll");
	if (user32_lib) {
		win8p_GetPointerType = (GetPointerTypePtr)GetProcAddress(user32_lib, "GetPointerType");
		win8p_GetPointerPenInfo = (GetPointerPenInfoPtr)GetProcAddress(user32_lib, "GetPointerPenInfo");
		winink_available = win8p_GetPointerType && win8p_GetPointerPenInfo;
	}
	if (winink_available) {
		tablet_drivers.push_back("winink");
	}
	if (OS::get_singleton()->is_hidpi_allowed()) {
		HMODULE Shcore = LoadLibraryW(L"Shcore.dll");
		if (Shcore != nullptr) {
			typedef HRESULT(WINAPI * SetProcessDpiAwareness_t)(SHC_PROCESS_DPI_AWARENESS);
			SetProcessDpiAwareness_t SetProcessDpiAwareness = (SetProcessDpiAwareness_t)GetProcAddress(Shcore, "SetProcessDpiAwareness");
			if (SetProcessDpiAwareness) {
				SetProcessDpiAwareness(SHC_PROCESS_SYSTEM_DPI_AWARE);
			}
		}
	}
	memset(&wc, 0, sizeof(WNDCLASSEXW));
	wc.cbSize = sizeof(WNDCLASSEXW);
	wc.style = CS_OWNDC | CS_DBLCLKS;
	wc.lpfnWndProc = (WNDPROC)::WndProc;
	wc.cbClsExtra = 0;
	wc.cbWndExtra = 0;
	wc.hInstance = hInstance ? hInstance : GetModuleHandle(nullptr);
	wc.hIcon = LoadIcon(nullptr, IDI_WINLOGO);
	wc.hCursor = nullptr;
	wc.hbrBackground = nullptr;
	wc.lpszMenuName = nullptr;