DEV: Upgrading Discourse to Zeitwerk (#8098)

Zeitwerk simplifies working with dependencies in dev and makes it easier reloading class chains. 

We no longer need to use Rails "require_dependency" anywhere and instead can just use standard 
Ruby patterns to require files.

This is a far reaching change and we expect some followups here.

script/demon_test/parent.rb

@@ -4,7 +4,7 @@ require File.expand_path("../../../config/environment", __FILE__)
 
 puts "Parent is now loaded"
 
-class ForkExecDemon < Demon::Base
+class ForkExecDemon < Demon::DemonBase
   def self.prefix
     "fork-exec-child"
   end

script/discourse

@@ -59,7 +59,7 @@ class DiscourseCLI < Thor
   desc "backup", "Backup a discourse forum"
   def backup(filename = nil)
     load_rails
-    require "backup_restore/backup_restore"
+    require "backup_restore"
     require "backup_restore/backuper"
 
     store = BackupRestore::BackupStore.create
@@ -117,7 +117,7 @@ class DiscourseCLI < Thor
     end
 
     load_rails
-    require "backup_restore/backup_restore"
+    require "backup_restore"
     require "backup_restore/restorer"
     require "backup_restore/backup_store"
 

script/import_scripts/base/uploader.rb

@@ -1,8 +1,5 @@
 # frozen_string_literal: true
 
-require_dependency 'url_helper'
-require_dependency 'upload_markdown'
-
 module ImportScripts
   class Uploader
     # Creates an upload.