Change public accounts pages to mount the web UI (#19319)

* Change public accounts pages to mount the web UI

* Fix handling of remote usernames in routes

- When logged in, serve web app
- When logged out, redirect to permalink
- Fix `app-body` class not being set sometimes due to name conflict

* Fix missing `multiColumn` prop

* Fix failing test

* Use `discoverable` attribute to control indexing directives

* Fix `<ColumnLoading />` not using `multiColumn`

* Add `noindex` to accounts in REST API

* Change noindex directive to not be rendered by default before a route is mounted

* Add loading indicator for detailed status in web UI

* Fix missing indicator appearing while account is loading in web UI

app/controllers/follower_accounts_controller.rb

@@ -3,6 +3,7 @@
 class FollowerAccountsController < ApplicationController
   include AccountControllerConcern
   include SignatureVerification
+  include WebAppControllerConcern
 
   before_action :require_account_signature!, if: -> { request.format == :json && authorized_fetch_mode? }
   before_action :set_cache_headers
@@ -14,10 +15,6 @@ class FollowerAccountsController < ApplicationController
     respond_to do |format|
       format.html do
         expires_in 0, public: true unless user_signed_in?
-
-        next if @account.hide_collections?
-
-        follows
       end
 
       format.json do