Cache featured collections, as well as outbox, followers and following (#10467)

app/controllers/following_accounts_controller.rb

@@ -3,9 +3,13 @@
 class FollowingAccountsController < ApplicationController
   include AccountControllerConcern
 
+  before_action :set_cache_headers
+
   def index
     respond_to do |format|
       format.html do
+        mark_cacheable! unless user_signed_in?
+
         next if @account.user_hides_network?
 
         follows
@@ -15,6 +19,11 @@ class FollowingAccountsController < ApplicationController
       format.json do
         raise Mastodon::NotPermittedError if params[:page].present? && @account.user_hides_network?
 
+        if params[:page].blank?
+          skip_session!
+          expires_in 3.minutes, public: true
+        end
+
         render json: collection_presenter,
                serializer: ActivityPub::CollectionSerializer,
                adapter: ActivityPub::Adapter,