As I was working on T335530, I realized that external tools have no way to tell whether logged-out users will get an auto-created account when editing or not. We should add it.

• action=query&prop=info&intestactions=...:
  • Add &intestactionsautocreate=1 to also check whether the actions would result in a creation of a temporary user account.

• action=query&meta=siteinfo:
  • Add &siprop=autocreatetempuser to output the configuration of temporary user accounts.