rofi_icon_fetcher is async, so we won't know which query succeeded on
the first try. All subsequent attempts use cached_icon_uid, and the
result of the first query will never be used.
Do the same as XCB window mode and request only lowercase app_id.
Use `window-format` to configure lines in the Wayland Window view.
Note that only `{t}` (title) and `{c}` (class) are supported on Wayland.
It is suggested to change the format string to `{c} {t}`.
The code still lacks a lot of features of XCB Window mode, but at least
following should work:
- Activate and Delete (close) actions
- matching by window title
- live update
- icon lookup by app_id
