Fix anti spam/virus wizard banner

Summary:
UserIcon doesn't work for loading this (it gives us a dummy icon here), so
instead load the banner image explicitly. To make that easier, compile it
into the binary.

Reviewers: mlaurent

Reviewed By: mlaurent

Subscribers: kde-pim

Tags: #kde_pim

Differential Revision: https://phabricator.kde.org/D24869