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/controllers/accounts_controller.rb

@@ -44,7 +44,6 @@ class AccountsController < ApplicationController
         limit     = params[:limit].present? ? [params[:limit].to_i, PAGE_SIZE_MAX].min : PAGE_SIZE
         @statuses = filtered_statuses.without_reblogs.limit(limit)
         @statuses = cache_collection(@statuses, Status)
-        render xml: RSS::AccountSerializer.render(@account, @statuses, params[:tag])
       end
 
       format.json do

app/controllers/tags_controller.rb

@@ -26,7 +26,6 @@ class TagsController < ApplicationController
 
       format.rss do
         expires_in 0, public: true
-        render xml: RSS::TagSerializer.render(@tag, @statuses)
       end
 
       format.json do