Allow to get Mastodon instance relays

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

lib/graphql/resolvers/admin.ex

@@ -469,7 +469,7 @@ defmodule Mobilizon.GraphQL.Resolvers.Admin do
       })
       when is_admin(role) do
     has_relay = Actors.has_relay?(domain)
-    remote_relay = Actors.get_actor_by_name("relay@#{domain}")
+    remote_relay = Actors.get_relay(domain)
     local_relay = Relay.get_actor()
 
     result = %{

lib/mobilizon/actors/actors.ex

@@ -1307,6 +1307,14 @@ defmodule Mobilizon.Actors do
     |> Repo.exists?()
   end
 
+  @doc """
+  Returns a relay actor, either `relay@domain` (Mobilizon) or `domain@domain` (Mastodon)
+  """
+  @spec get_relay(String.t()) :: Actor.t() | nil
+  def get_relay(domain) do
+    get_actor_by_name("relay@#{domain}") || get_actor_by_name("#{domain}@#{domain}")
+  end
+
   @spec delete_files_if_media_changed(Ecto.Changeset.t()) :: Ecto.Changeset.t()
   defp delete_files_if_media_changed(%Ecto.Changeset{changes: changes, data: data} = changeset) do
     Enum.each([:avatar, :banner], fn key ->