Add account migration UI (#11846)

Fix #10736

- Change data export to be available for non-functional accounts
- Change non-functional accounts to include redirecting accounts

app/controllers/settings/aliases_controller.rb

@@ -0,0 +1,42 @@
+# frozen_string_literal: true
+
+class Settings::AliasesController < Settings::BaseController
+  layout 'admin'
+
+  before_action :authenticate_user!
+  before_action :set_aliases, except: :destroy
+  before_action :set_alias, only: :destroy
+
+  def index
+    @alias = current_account.aliases.build
+  end
+
+  def create
+    @alias = current_account.aliases.build(resource_params)
+
+    if @alias.save
+      redirect_to settings_aliases_path, notice: I18n.t('aliases.created_msg')
+    else
+      render :show
+    end
+  end
+
+  def destroy
+    @alias.destroy!
+    redirect_to settings_aliases_path, notice: I18n.t('aliases.deleted_msg')
+  end
+
+  private
+
+  def resource_params
+    params.require(:account_alias).permit(:acct)
+  end
+
+  def set_alias
+    @alias = current_account.aliases.find(params[:id])
+  end
+
+  def set_aliases
+    @aliases = current_account.aliases.order(id: :desc).reject(&:new_record?)
+  end
+end