We have "shared/nm-libnm-core-aux", which is shared code that can be used
by anybody (including libnm-core, src, libnm and clients).
We have "clients/common", which are helper function for clients. But
that implies that the code is inside "clients". I think it would be
useful to have auxiliary code that extends libnm, but is not only
usable by code in "clients". In other words, "shared/nm-libnm-aux"
is a better place than "clients/common", and I think most of the
functionality form "clients/common" should move there.