task-kannada*: Migrate from fcitx4 to fcitx5
For task-kannada*, they are now using fcitx 4.x. Considering that fcitx 4.x upstream support is now officially dead and upstream has archived related projects [1], we should move the use fcitx5's support instead.
This commit contains the following changes:
- fcitx -> fcitx5
- fcitx-m17n -> fcitx5-m17n
- kde-config-fcitx -> kde-config-fcitx5
Besides, the dependency to fcitx4 GTK config GUI tool is removed since the fcitx5 upstream is only providing a Qt/KDE frontend GUI config tool at this moment.
[1] https://lists.debian.org/debian-input-method/2024/10/msg00042.html
Bug-Debian: https://bugs.debian.org/1117875