Add explicit iconOnly option for the taskmanager

[thomas-bouvier]

Hello,

I am looking for some guidance to implement an option enabling the Icons-and-Text task manager widget. At the moment, only the Icons task manager widget seems supported by this project.

I couldn't find any documentation on the matter, and this is my first Nix contribution. Looking at this file, it seems that the icons-only mode is activated when package org.kde.plasma.icontasks is used in place of org.kde.plasma.taskmanager. However, I'd like to see some validation of the robustness of this approach.

Also, the iconOnly boolean may need to be inverted to keep the default behavior to icons-only mode.

I'm currently testing to see if all the options apply to org.kde.plasma.taskmanager.

[HeitorAugustoLN]

I guess this should fix the PR, the mkBoolOption sets a null value by default, that why the error was happening, that should do the work for taskmanager widget working. If you think it is good to go, you can mark the PR as ready for review and I would be happy to merge :)

[thomas-bouvier]

Hello @HeitorAugustoLN, thank you for the fix, all is good on my side :)