### 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)

MDT_Effective_DPI = 0,
	MDT_Angular_DPI = 1,
	MDT_Raw_DPI = 2,
	MDT_Default = MDT_Effective_DPI
};
static int QueryDpiForMonitor(HMONITOR hmon, _MonitorDpiType dpiType = MDT_Default) {
	int dpiX = 96, dpiY = 96;
	static HMODULE Shcore = nullptr;
	typedef HRESULT(WINAPI * GetDPIForMonitor_t)(HMONITOR hmonitor, _MonitorDpiType dpiType, UINT * dpiX, UINT * dpiY);
	static GetDPIForMonitor_t getDPIForMonitor = nullptr;
	if (Shcore == nullptr) {
		Shcore = LoadLibraryW(L"Shcore.dll");
		getDPIForMonitor = Shcore ? (GetDPIForMonitor_t)GetProcAddress(Shcore, "GetDpiForMonitor") : nullptr;
		if ((Shcore == nullptr) || (getDPIForMonitor == nullptr)) {
			if (Shcore) {