Fix running the tests with CMAKE_RUNTIME_OUTPUT_DIRECTORY set

Summary:
With the newer ECM requirement introduced in [1]
CMAKE_RUNTIME_OUTPUT_DIRECTORY gets set [2], which causes the tests
to fail because they don't find the test executables. Adding the
NAME and COMMAND keywords, which aren't really optional according to
cmake's docs, makes them pass again.

[1] dc40d092
[2] https://phabricator.kde.org/D7198

Differential Revision: https://phabricator.kde.org/D20662