Add a per-user setting to hide followers count

This is only available if the instance-wide setting isn't set and allows
people to hide their own followers count. This does not hide others' to
them.

app/controllers/follower_accounts_controller.rb

@@ -37,7 +37,7 @@ class FollowerAccountsController < ApplicationController
 
   def collection_presenter
     options = { type: :ordered }
-    options[:size] = @account.followers_count unless Setting.hide_followers_count
+    options[:size] = @account.followers_count unless Setting.hide_followers_count || @account.user&.setting_hide_followers_count
     if params[:page].present?
       ActivityPub::CollectionPresenter.new(
         id: account_followers_url(@account, page: params.fetch(:page, 1)),

app/controllers/settings/preferences_controller.rb

@@ -43,6 +43,7 @@ class Settings::PreferencesController < Settings::BaseController
       :setting_system_font_ui,
       :setting_noindex,
       :setting_hide_network,
+      :setting_hide_followers_count,
       :setting_aggregate_reblogs,
       notification_emails: %i(follow follow_request reblog favourite mention digest report),
       interactions: %i(must_be_follower must_be_following)