Lists (#5703)

* Add structure for lists

* Add list timeline streaming API

* Add list APIs, bind list-account relation to follow relation

* Add API for adding/removing accounts from lists

* Add pagination to lists API

* Add pagination to list accounts API

* Adjust scopes for new APIs

- Creating and modifying lists merely requires "write" scope
- Fetching information about lists merely requires "read" scope

* Add test for wrong user context on list timeline

* Clean up tests

config/routes.rb

@@ -212,6 +212,7 @@ Rails.application.routes.draw do
         resource :home, only: :show, controller: :home
         resource :public, only: :show, controller: :public
         resources :tag, only: :show
+        resources :list, only: :show
       end
 
       resources :streaming, only: [:index]
@@ -270,6 +271,10 @@ Rails.application.routes.draw do
           post :unmute
         end
       end
+
+      resources :lists, only: [:index, :create, :show, :update, :destroy] do
+        resource :accounts, only: [:show, :create, :destroy], controller: 'lists/accounts'
+      end
     end
 
     namespace :web do