[LyX/master] Fix clear button in FancyLineEdit

[Jürgen Spitzmüller]

Am Mittwoch, dem 12.03.2025 um 14:20 +0000 schrieb Juergen
Spitzmueller:
> commit 96262763c3a5e79d44e9429255e4ad1b591bf857
> Author: Juergen Spitzmueller <spitz at lyx.org>
> Date:   Wed Mar 12 15:18:34 2025 +0100
> 
>     Fix clear button in FancyLineEdit
>     
>     Use the icon from the theme and consider dark mode

Should also go to stable.

-- 
Jürgen