Change RSS feeds (#18356)

* Change RSS feeds

- Use date and time for titles instead of ellipsized text
- Use full content in body, even when there is a content warning
- Use media extensions

* Change feed icons and add width and height attributes to custom emojis

* Fix custom emoji animate on hover breaking

* Fix tests

app/serializers/rss/account_serializer.rb

@@ -1,28 +0,0 @@
-# frozen_string_literal: true
-
-class RSS::AccountSerializer < RSS::Serializer
-  include ActionView::Helpers::NumberHelper
-  include AccountsHelper
-  include RoutingHelper
-
-  def render(account, statuses, tag)
-    builder = RSSBuilder.new
-
-    builder.title("#{display_name(account)} (@#{account.local_username_and_domain})")
-           .description(account_description(account))
-           .link(tag.present? ? short_account_tag_url(account, tag) : short_account_url(account))
-           .logo(full_pack_url('media/images/logo.svg'))
-           .accent_color('2b90d9')
-
-    builder.image(full_asset_url(account.avatar.url(:original))) if account.avatar?
-    builder.cover(full_asset_url(account.header.url(:original))) if account.header?
-
-    render_statuses(builder, statuses)
-
-    builder.to_xml
-  end
-
-  def self.render(account, statuses, tag)
-    new.render(account, statuses, tag)
-  end
-end

app/serializers/rss/tag_serializer.rb

@@ -1,25 +0,0 @@
-# frozen_string_literal: true
-
-class RSS::TagSerializer < RSS::Serializer
-  include ActionView::Helpers::NumberHelper
-  include ActionView::Helpers::SanitizeHelper
-  include RoutingHelper
-
-  def render(tag, statuses)
-    builder = RSSBuilder.new
-
-    builder.title("##{tag.name}")
-           .description(strip_tags(I18n.t('about.about_hashtag_html', hashtag: tag.name)))
-           .link(tag_url(tag))
-           .logo(full_pack_url('media/images/logo.svg'))
-           .accent_color('2b90d9')
-
-    render_statuses(builder, statuses)
-
-    builder.to_xml
-  end
-
-  def self.render(tag, statuses)
-    new.render(tag, statuses)
-  end
-end