String freeze exception request

[Nate Graham]

Hello release team,
I'd like to request a string freeze exception for 
https://phabricator.kde.org/D26717. This patch ports the Style KCM to 
use the new GHNS UI that the rest of the Plasma KCMs will be using in 
5.18. It contains two minor changed strings and two small new strings. 
If we don't land it for Plasma 5.18, then it will be the only KCM stuck 
using the old style GHNS dialog which will be kind of weird.

Nate