Tests: update tests for the current API

It also fixes many code indentation issues so I really recommend to
review changes with '--ignore-all-space' equivalent.
Tests: code polishing - use normalized signal signatures
QOfonoNetworkOperator: Remove recently added value semantics

Introduced with 856f137 ([libqofono] add auto tests.) in order to make
tests build possible. Hopefully nobody used it elsewhere and so it is
safe to simply remove it.