activerecord: refine create/create! RBS signatures and update tests

[kozy4324]

• Allow passing a block to create / create! .
• Add overloads for attributes as an Array of hashes and array return types.
• Add tests for create / create! .

Note on file placement

The create / create! signatures are defined in activerecord-8.0.rbs rather than activerecord.rbs, because these methods are statically defined in Ruby source, not dynamically generated at runtime. The activerecord.rbs file already declares extend ::ActiveRecord::Persistence::ClassMethods on ActiveRecord::Base, so the type checker resolves them through that module naturally. Is this reasoning correct?

[github-actions]

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See also: https://github.com/ruby/gem_rbs_collection/blob/main/docs/CONTRIBUTING.md

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activerecord

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