node_authlink_create() should assign the node->authkey

Problem/Motivation

When calling node_authlink_create() it would be convenient to set the node object's authlink property so it doesn't needed be loaded via a separate call to node_authlink_node_load()

Steps to reproduce

    node_authlink_create($node);
    // Needed to get the authlink. $node->authkey = node_authlink_load_authkey($node->id());
    $auth_edit_link = node_authlink_get_url($node, 'update')->toString();

Proposed resolution

Assign $node->authkeyinside node_authlink_create()

Remaining tasks

User interface changes

API changes

Data model changes