On Windows, some windows may be created that are not managed by the
application.
For example, the Japanese IME creates pop-ups like this one.

<img width="325" alt="image"
src="https://github.com/zed-industries/zed/assets/6465609/503aaa0a-7568-485a-a138-e689ae67001c">

The internal data associated with such a window is different from
`WindowsWindowInner` and will crash if referenced.
Therefore, before calling `try_get_window_inner`, it checks if it is an
owned window.


Release Notes:

- N/A