[KonsoleProfiles applet] Fix navigating with the keyboard

Summary: BUG: 399192

Test Plan:
Create several profiles in Konsole.
Open the Konsole Profiles applet, using the keyboard arrows
should now move the selected item.

Reviewers: #plasma, davidedmundson

Reviewed By: #plasma, davidedmundson

Subscribers: plasma-devel

Tags: #plasma

Differential Revision: https://phabricator.kde.org/D15877