Don't STI load via the descendants/subclasses hooks during code reload

The descendant_loader.rb hooks descendants and subclasses to do proper sti loading of
subclasses and descendants. It should not be used when code reload is happening.

This fixes a bug when issuing reload! in rails console with rails 7.

config/application.rb

@@ -33,6 +33,8 @@
 
 module Vmdb
   class Application < Rails::Application
+    attr_accessor :reloading
+
     # Settings in config/environments/* take precedence over those specified here.
     # Application configuration should go into files in config/initializers
     # -- all .rb files in that directory are automatically loaded.
@@ -191,6 +193,12 @@ class Application < Rails::Application
       # Reload Settings to get values from db now that it's safe to autoload
       ::Settings.reload!
       Vmdb::Loggers.apply_config(::Settings.log)
+
+      # The descendant_loader.rb hooks descendants and subclasses to do proper sti loading of
+      # subclasses and descendants. It should not be used when code reload is happening.
+      Vmdb::Application.reloading = false
+      Vmdb::Application.reloader.before_class_unload { Vmdb::Application.reloading = true }
+      Vmdb::Application.reloader.to_complete         { Vmdb::Application.reloading = false }
     end
 
     console do

lib/extensions/descendant_loader.rb

@@ -278,7 +278,7 @@ module ArDescendantsWithLoader
     #   "xxx/manageiq/app/models/vm_or_template.rb:15:in `<class:VmOrTemplate>'",
     #   "xxx/manageiq/app/models/vm_or_template.rb:6:in `<main>'",
     def descendants
-      if Vmdb::Application.instance.initialized? && !defined?(@loaded_descendants) && %w[__update_callbacks].exclude?(caller_locations(1..1).first.base_label)
+      if Vmdb::Application.instance.initialized? && !defined?(@loaded_descendants) && %w[__update_callbacks].exclude?(caller_locations(1..1).first.base_label) && !Vmdb::Application.reloading
         @loaded_descendants = true
         DescendantLoader.instance.load_subclasses(self)
       end
@@ -327,7 +327,7 @@ def descendants
     #   "xxx/gems/activesupport-7.0.8.4/lib/active_support/descendants_tracker.rb:89:in `descendants'",
     #   ...
     def subclasses
-      if Vmdb::Application.instance.initialized? && !defined?(@loaded_descendants) && %w[descendants reload_schema_from_cache subclasses].exclude?(caller_locations(1..1).first.base_label)
+      if Vmdb::Application.instance.initialized? && !defined?(@loaded_descendants) && %w[descendants reload_schema_from_cache subclasses].exclude?(caller_locations(1..1).first.base_label) && !Vmdb::Application.reloading
         @loaded_descendants = true
         DescendantLoader.instance.load_subclasses(self)
       end