Add needed columns to QueryBuilder explicitly

Summary:
The former fullColumnNames approach relied on the number and order of
columns returned by fullColumnNames to not change. Requesting the
required column explicitly makes this more robust.

Reviewers: dvratil

Reviewed By: dvratil

Subscribers: #kde_pim

Tags: #kde_pim

Differential Revision: https://phabricator.kde.org/D7492