Add (back) option to set redirect notice on account without moving followers (#11994)

Fix #11913

app/controllers/settings/migration/redirects_controller.rb

@@ -0,0 +1,45 @@
+# frozen_string_literal: true
+
+class Settings::Migration::RedirectsController < Settings::BaseController
+  layout 'admin'
+
+  before_action :authenticate_user!
+  before_action :require_not_suspended!
+
+  skip_before_action :require_functional!
+
+  def new
+    @redirect = Form::Redirect.new
+  end
+
+  def create
+    @redirect = Form::Redirect.new(resource_params.merge(account: current_account))
+
+    if @redirect.valid_with_challenge?(current_user)
+      current_account.update!(moved_to_account: @redirect.target_account)
+      ActivityPub::UpdateDistributionWorker.perform_async(current_account.id)
+      redirect_to settings_migration_path, notice: I18n.t('migrations.moved_msg', acct: current_account.moved_to_account.acct)
+    else
+      render :new
+    end
+  end
+
+  def destroy
+    if current_account.moved_to_account_id.present?
+      current_account.update!(moved_to_account: nil)
+      ActivityPub::UpdateDistributionWorker.perform_async(current_account.id)
+    end
+
+    redirect_to settings_migration_path, notice: I18n.t('migrations.cancelled_msg')
+  end
+
+  private
+
+  def resource_params
+    params.require(:form_redirect).permit(:acct, :current_password, :current_username)
+  end
+
+  def require_not_suspended!
+    forbidden if current_account.suspended?
+  end
+end