user: factor out illogical User.Info.superuser?/1.

any actual callee will be dealing with a User struct to begin with, so
just check the child struct inside User.superuser?/1 with pattern matching.

lib/pleroma/user.ex

@@ -63,7 +63,8 @@ defmodule Pleroma.User do
 
   def visible_for?(_, _), do: false
 
-  def superuser?(%User{info: %User.Info{} = info}), do: User.Info.superuser?(info)
+  def superuser?(%User{local: true, info: %User.Info{is_admin: true}}), do: true
+  def superuser?(%User{local: true, info: %User.Info{is_moderator: true}}), do: true
   def superuser?(_), do: false
 
   def avatar_url(user) do

lib/pleroma/user/info.ex

@@ -41,8 +41,6 @@ defmodule Pleroma.User.Info do
     # subject _> Where is this used?
   end
 
-  def superuser?(info), do: info.is_admin || info.is_moderator
-
   def set_activation_status(info, deactivated) do
     params = %{deactivated: deactivated}