Allow using different webfinger domain than url hostname
If :webfinger_domain
is set for Pleroma.Web.Endpoint, that domain will be used when computing the full ActivityPub actor name ("@user@domain.tld"). Otherwise, the hostname configured in :url
is used, as before.
This allows an instance to, e.g., serve at https://pleroma.domain.tld/, but assign actor names directly under domain.tld
.