### 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)

wd.max_pressure = int(pressure.axMax);
				}
				AXIS orientation[3];
				if (wintab_WTInfo(WTI_DEVICES + wd.wtlc.lcDevice, DVC_ORIENTATION, &orientation)) {
					wd.tilt_supported = orientation[0].axResolution && orientation[1].axResolution;
				}
			} else {
				print_verbose("WinTab context creation failed.");
			}
		} else {
			wd.wtctx = 0;
		}
		if (p_mode == WINDOW_MODE_MAXIMIZED) {
			wd.maximized = true;
			wd.minimized = false;
		}
		if (p_mode == WINDOW_MODE_MINIMIZED) {
			wd.maximized = false;
			wd.minimized = true;
		}
		wd.last_pressure = 0;
		wd.last_pressure_update = 0;
		wd.last_tilt = Vector2();
		
		wd.im_himc = ImmGetContext(wd.hWnd);
		ImmAssociateContext(wd.hWnd, (HIMC)0);
		wd.im_position = Vector2();
		if (p_mode == WINDOW_MODE_FULLSCREEN || p_mode == WINDOW_MODE_EXCLUSIVE_FULLSCREEN || p_mode == WINDOW_MODE_MAXIMIZED) {
			RECT r;
			GetClientRect(wd.hWnd, &r);