Add quick links to the admin interface in the WebUI (#8545)

* Allow to show a specific status in the admin interface

* Let the front-end know the current account is a moderator

* Add admin links to status and account menus

If the current logged-in user is an admin, add quick links to the admin
interface in account and toot dropdown menu. Suggestion by @ashkitten

* Use @statuses.first instead of @statuses[0]

config/routes.rb

@@ -192,7 +192,7 @@ Rails.application.routes.draw do
       resource :change_email, only: [:show, :update]
       resource :reset, only: [:create]
       resource :action, only: [:new, :create], controller: 'account_actions'
-      resources :statuses, only: [:index, :create, :update, :destroy]
+      resources :statuses, only: [:index, :show, :create, :update, :destroy]
       resources :followers, only: [:index]
 
       resource :confirmation, only: [:create] do