SaveOperation fails to compile if using enum column defined within model

I have a class `Order` and a column called `state` where the value is an enum `OrderState`. I originally had the enum defined within the model but upon creating and trying to use a SaveOperation it failed to compile with this error message

```
web | Showing last frame. Use --error-trace for full trace.
web | There was a problem expanding macro 'generate_create'
web |
web | Code in macro 'generate_save_methods'
web |
web | 2 | generate_create("id : Int64 | Avram::Nothing = Avram::Nothing.new,\ncreated_at : Time | Avram::Nothing = Avram::Nothing.new,\nupdated_at : Time | Avram::Nothing = Avram::Nothing.new,\nstate : OrderState | Avram::Nothing = Avram::Nothing.new,\nguest_token : String | Avram::Nothing | Nil = Avram::Nothing.new,\nuser_id : User::PrimaryKeyType | Avram::Nothing | Nil = Avram::Nothing.new,\n", "id: id,\ncreated_at: created_at,\nupdated_at: updated_at,\nstate: state,\nguest_token: guest_token,\nuser_id: user_id,\n", with_params: true, with_bang: true)
web | ^
web | Called macro defined in lib/avram/src/avram/needy_initializer_and_save_methods.cr:96:3
web |
web | 96 | macro generate_create(attribute_method_args, attribute_params, with_params, with_bang)
web |
web | Which expanded to:
web |
web | > 13 | created_at : Time | Avram::Nothing = Avram::Nothing.new,
web | > 14 | updated_at : Time | Avram::Nothing = Avram::Nothing.new,
web | > 15 | state : OrderState | Avram::Nothing = Avram::Nothing.new,
web | ^---------
web | Error: undefined constant OrderState
```

This is from version 1.0.0-rc1

Reproduce the failure with an Order model whose state column uses an enum defined inside the model, then inspect lib/avram/src/avram/needy_initializer_and_save_methods.cr around generate_create and generate_save_methods. Confirm the compiler error and determine whether the SaveOperation can compile with the nested enum; done means the shown model builds successfully without an undefined constant OrderState error.

Written by the indexing model from the issue text.