Refactor and fix the mobile wifi kcm
Previous refactoring and existing errors made editing connections impossible. Also, existing work for adding hidden networks was broken. By fixing these problems, this patch implements T12893.
The checks for signal strength being > 0 were removed to make make hidden networks show up in the list
Test Plan: Test adding and editing connections
Reviewers: Plasma, ngraham, jgrulich, jbbgameich
Reviewed By: jgrulich, jbbgameich
Subscribers: nicolasfella, plasma-devel
Differential Revision: https://phabricator.kde.org/D28799