The create calls were introduced in 62fa766d8f3 but work on this started
a while before 038446c50630 allowed passing the _defaults_only flag to
publish.
Less drastic change from mod_vcard where everything is always public.
This allows users to configure nodes without needing to for the old
behaviour.
Thanks to 038446c50630 users may still override this.
Due to #1222 this may still not apply if the node has already been
created by an automatic subscription
Normally both nodes should have the same configuration and matching
items, but we can't depend on it without having some code that enforces
it, which does not exist at the time of this commit.
Including the avatar itself should be prioritised. The image format can
be derived from magic bytes.
Since vcards are just avatar containers in many modern clients, aborting
in case of no vcard4 data is not optimal.
The upgrade mechanism needs further tweaks.