kcms/rules: improve text for window rules with descriptions
In particular, explain what all of the the focus stealing prevention and protection settings do.
My understanding of the different modes comes from reading the code and code comments in activation.cpp.
The tooltips for the focus stealing prevention/protection properties are quite huge now, so if anyone has any ideas how we can reduce them without losing meaning, I'm all ears. But I do think regardless of what else we do, we have to describe each setting in detail since their names aren't descriptive enough to communicate their functions.
No before-and-after images because this MR only changes text, and it's easy enough to compare text in the diff view.