The plugins page in the settings dialog shows a plugin "Icon picker", because this is installed from workspace/plasma-sdk into plugins/ktexteditor/ but completely useless for kate
I does work, aka you get a context menu and that will insert a icon name. But it is really very useless for most people, therefore for 19.08 it will be at least no longer loaded by default. (no idea why we loaded it ever by default, given its user base is 1% of our users)