how about a developer KCM

[David Edmundson]

I have one hidden KCM already.

It was requested I make the super awesome qtquicksettings module hidden.
It uses a little hack to make it findable in krunner, but not listed
in system settings by parenting to a group, then hiding that group.

I  have no objections to things that are only useful to devs being in
a hidden KCM.

However, I fear it will end up becoming some sort of hidden
plasma-tweaks, where we dump general aesthetic/behaviour settings in
here which we think are too niche for the main UI.
I don't want that to happen.