Use error messages to be consistent, and avoid checking for a returned
value when dbus-glib function to fetch it returned false, as it's
implicit that we had a failure.
Otherwise if didn't fail we are sure that we got the requested value.
Given that finger_name is set by GOptionEntry, make sure it's always
using allocated memory.
../utils/enroll.c:38:28: error: initialization discards ‘const’ qualifier
from pointer target type [-Werror=discarded-qualifiers]
38 | static char *finger_name = "right-index-finger";
| ^~~~~~~~~~~~~~~~~~~~
These utilities are generally useful beyond only testing purproses. And,
since it is desirable to have automated tests inside the tests
subdirecty, it makes sense to move them elsewhere.
