Add test for MyMoneyTransactionFilter

This test was created to check the basic functions of the transaction
filter, but does not claim to be complete. It was written by me for 4.8
and ported from Thomas Baumgart to KF5.

CCBUG:395327
Test Plan: compiled and tested on linux
Reviewers: wojnilowicz
Signed-off-by: Ralf Habacker <ralf.habacker@freenet.de>
Differential Revision: https://phabricator.kde.org/D15107