Make scopes available for abstract classes

[Teots]

Motivation

At the moment sorbet can't figure out that classes, that are marked as abstract, have access to scopes. The following example illustrates this:

class A < ApplicationRecord
  extend T::Sig
  abstract_class = true

  scope :deleted, -> { where.not(deleted_at: nil) }

  class << self
    extend T::Sig

    sig { returns(Integer) }
    def count_deleted
        # Method `deleted` does not exist on `T.class_of(A)`
        deleted.count
    end
  end
end

Since those scopes can be used, I think it makes sense to generate the rbi files accordingly.

Implementation

I removed the filter for abstract classes in ActiveRecordScope and did the same thing in ActiveRecordRelations to make the generated relation methods work.

Tests

Tests for ActiveRecordScope have been extended.

[paracycle]

did the same thing in ActiveRecordRelations to make the generated relation methods work.

Can't see this part in the PR. Is that missing or did you decide against this?

[Teots]

@paracycle Sorry, looks like I forgot to push this commit 🙈 It's there now.

[paracycle]

Looks good to me! We will have to check this against Core to make sure that we don't get any unwanted behaviour before merging though.

[antn]

Ah, I just ran into this too. @paracycle, did this end up having unexpected behavior, or is it maybe good to merge? 😄

[paracycle]

Ok, I just had a chance to test this against Shopify Core and it seems to work. However, I removed the commit that was making AR relations to consider abstract classes as well, since that's not related to scopes and I don't think we would want folks to write relations off of abstract classes.