Add list of lists component to web UI (#5811)

* Add list of lists component to web UI

* Add list adding

* Add list removing

* List editor modal

* Add API account search limited by following=true relation

* Rework list editor modal

* Remove mandatory pagination of GET /api/v1/lists/:id/accounts

* Adjust search input placeholder

* Fix rspec (#5890)

* i18n: (zh-CN) Add missing translations for #5811 (#5891)

* i18n: (zh-CN) yarn manage:translations -- zh-CN

* i18n: (zh-CN) Add missing translations for #5811

* Fix some issues

- Display loading/missing state for list timelines
- Order lists alphabetically in overview
- Fix async list editor reset
- Redirect to /lists after deleting unpinned list
- Redirect to / after pinning a list

* Remove dead list columns when a list is deleted or fetch returns 404

app/models/list_account.rb

@@ -14,6 +14,8 @@ class ListAccount < ApplicationRecord
   belongs_to :account, required: true
   belongs_to :follow, required: true
 
+  validates :account_id, uniqueness: { scope: :list_id }
+
   before_validation :set_follow
 
   private