plugins/runcommand: use Kirigami.Dialog
The "Add Command" dialog in the settings for the Run Command plugin looks rather broken at the moment, as the size is not explicitly set and the default value ends up much smaller than the contents. It uses QQC2.Dialog, even though the plugin makes heavy use of Kirigami. Using Kirigami.dialog here would solve the sizing issue, and generally lead to a more consistent interface.
This change makes the plugin use Kirigami.Dialog instead of QQC2.
Visuals for comparison:
Sad QQC2.Dialog :(
Happy Kirigami.Dialog :)
There's some other things I would like to improve here (HIG consistency fixes etc.) but these might require minor string changes, while I hope this one might qualify as a bug fix for the upcoming release.