feat(nodeinfo): extract and save NodeInfo information from instances to display it on instances list

We also try to detect the application actor if it's not given by NodeInfo metadata (FEP-2677)
(guessing for Mobilizon, PeerTube & Mastodon).

Closes #1392

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

priv/repo/migrations/20231220092536_add_actor_instances.exs

@@ -0,0 +1,17 @@
+defmodule Mobilizon.Storage.Repo.Migrations.AddActorInstances do
+  use Ecto.Migration
+
+  def change do
+    create table(:instance_actors) do
+      add(:domain, :string)
+      add(:instance_name, :string)
+      add(:instance_description, :string)
+      add(:software, :string)
+      add(:software_version, :string)
+      add(:actor_id, references(:actors, on_delete: :delete_all))
+      timestamps()
+    end
+
+    create(unique_index(:instance_actors, [:domain]))
+  end
+end