Unable to autoload constant Base

This issue was originally reported at https://github.com/activeadmin/activeadmin/issues/2908

Current workarounds (from the engine) are:

- Rename `Base` classes
- Add an empty `Base` class

```
class Base
end

module MyCustomEngine
class Engine < ::Rails::Engine
```

I guess it could be fixed rescuing `NameError, LoadError` at method `initialize_resources_class_accessors!` from `inherited_resources/lib/inherited_resources/class_methods.rb` (as done at https://github.com/activeadmin/inherited_resources/pull/416)