REFACTOR: Migrate InstagramAuthenticator to use ManagedAuthenticator (#7081)

db/migrate/20190227150413_migrate_instagram_user_info.rb

@@ -0,0 +1,27 @@
+class MigrateInstagramUserInfo < ActiveRecord::Migration[5.2]
+  def up
+    execute <<~SQL
+    INSERT INTO user_associated_accounts (
+      provider_name,
+      provider_uid,
+      user_id,
+      info,
+      last_used,
+      created_at,
+      updated_at
+    ) SELECT
+      'instagram',
+      instagram_user_id,
+      user_id,
+      json_build_object('nickname', screen_name),
+      updated_at,
+      created_at,
+      updated_at
+    FROM instagram_user_infos
+    SQL
+  end
+
+  def down
+    raise ActiveRecord::IrreversibleMigration
+  end
+end