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

app/models/media_attachment.rb

@@ -3,19 +3,19 @@
 #
 # Table name: media_attachments
 #
-#  id                :bigint           not null, primary key
-#  status_id         :bigint
+#  id                :integer          not null, primary key
+#  status_id         :integer
 #  file_file_name    :string
 #  file_content_type :string
 #  file_file_size    :integer
 #  file_updated_at   :datetime
 #  remote_url        :string           default(""), not null
-#  account_id        :bigint
 #  created_at        :datetime         not null
 #  updated_at        :datetime         not null
 #  shortcode         :string
 #  type              :integer          default("image"), not null
 #  file_meta         :json
+#  account_id        :integer
 #  description       :text
 #