Updated RunCommand.qml to scroll with Ctrl + home row (j, k)

Summary:
This change allows users to scroll through krunner output using their homerow.

• Ctrl+j: Scroll Down
• Ctrl+k: Scroll Up

This makes scrolling easier for those familiar with this convention but doesn't inhibit users who aren't.

Reviewers: broulik, Plasma: Workspaces, davidedmundson

Reviewed By: Plasma: Workspaces, davidedmundson

Subscribers: davidedmundson, Plasma: Workspaces, plasma-devel

Tags: Plasma

Differential Revision: https://phabricator.kde.org/D13686