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/models/user.rb

@@ -94,7 +94,7 @@ class User < ApplicationRecord
   has_many :session_activations, dependent: :destroy
 
   delegate :auto_play_gif, :default_sensitive, :unfollow_modal, :boost_modal, :favourite_modal, :delete_modal,
-           :reduce_motion, :system_font_ui, :noindex, :flavour, :skin, :display_media, :hide_network,
+           :reduce_motion, :system_font_ui, :noindex, :flavour, :skin, :display_media, :hide_network, :hide_followers_count,
            :expand_spoilers, :default_language, :aggregate_reblogs, to: :settings, prefix: :setting, allow_nil: false
 
   attr_reader :invite_code