Decorate ActiveRecord::Batches methods

[bdewater]

Motivation

I wanted typing for the yielded values from the methods in https://github.com/rails/rails/blob/main/activerecord/lib/active_record/relation/batches.rb

Partially addresses #1281

Implementation

Mostly straightforward, return types are nilable in case the block form is used, eg:

Post.find_each { |post| do_something(post) }
#=> nil

Post.find_each
#=> #<Enumerator: ...>

Tests

Added tests.

[bdewater]

Seeing some unrelated bundler step failures, eg:

  Resolving dependencies...
  Could not find compatible versions
  
  Because every version of rails depends on RubyGems >= 3.3.13
    and Gemfile-rails-main depends on rails >= 0,
    RubyGems >= 3.3.13 is required.
  So, because current RubyGems version is = 3.1.6,
    version solving has failed.

[st0012]

@bdewater Rebasing main should resolve the test failures.

[bdewater]

@st0012 done!

[KaanOzkan]

Thanks it looks good to me. Few minor comments.

[KaanOzkan]

Not related to this PR but it may be worth investing in a rails_helper similar to https://github.com/Shopify/tapioca/blob/main/lib/tapioca/helpers/sorbet_helper.rb if these keep coming up. We had a similar occurrence in #1327.