Authorization domains are no longer used in password storage.

Authorization domains are no longer used in password storage.

They are a relic of keyfile-based password storage, where the auth
domain was merely the keyfile group name.  Keyring-based password
storage, which we now use exclusively, has no such concept.

Rename all "component_name" parameters in e-passwords.c to "unused" and
remove their argument guards from functions.

Remove all AUTH_DOMAIN definitions from ECredentials.  Better to nip
that in the bud before we're stuck with those symbols.  DO NOT bump the
libedataserver soname, however, since that would be highly disruptive to
distros and nothing uses ECredentials yet.

Remove the "domain" parameter from CamelSession password methods.  Also
remove any mention of "auth_domain" URL parameters.  This is a genuine
API break requiring a libcamel soname bump, but no one cares.