elide Network Manager KCM tabs
Summary:
Before when the main UI was too small we would lose tabs with no indication
Now the tab text elides
Test Plan: Opened the KCM
Reviewers: Plasma, jgrulich
Reviewed By: jgrulich
Subscribers: jgrulich, plasma-devel
Tags: Plasma
Differential Revision: https://phabricator.kde.org/D4374