Style/HashEachMethods: Detect use of .each + _ variables

[splattael]

Is your feature request related to a problem? Please describe.

Let Style/HashEachMethods flag code like:

# bad
hash.each do |key, _|
end
hash.each do |key, _value|
end

# bad
hash.each do |_, value|
end
hash.each do |_key, value|
end

# good
hash.each_key do |key|
end

hash.each_value do |value|
end

Describe the solution you'd like

The cop should suggest faster alternatives to each when used with underscore variables.

Describe alternatives you've considered

Alternatively, we could create a new cop rule but I feel it be a nice extension to Style/HashEachMethods.

Additional context

Potential impact on projects done via rg "each do \|(_(\w+)?, \w+|\w+, _(\w+)?)\|".

RuboCop

spec/rubocop/cop/lint/unused_block_argument_spec.rb:            hash.each do |key, _value|
spec/rubocop/cop/lint/unused_block_argument_spec.rb:            hash.each do |_key, value|
spec/rubocop/cop/lint/unused_block_argument_spec.rb:            hash.each do |_key, _value|
lib/rubocop/cop/style/bisected_attr_accessor.rb:          find_macros(class_node.body).each do |_visibility, macros|

GitLab

lib/feature/definition.rb:    TYPES.each do |type, _|
lib/tasks/gitlab/setup.rake:    Gitlab.config.repositories.storages.each do |name, _details|
lib/tasks/gitlab/db.rake:        Gitlab::Database.database_base_models.each do |_, model_class|
lib/gitlab/dependency_linker/podspec_json_linker.rb:        dependencies.each do |name, _|
lib/backup/database.rb:      base_models_for_backup.each do |database_name, _base_model|
lib/backup/manager.rb:      definitions.each do |_, definition|
lib/gitlab/language_data.rb:              YAML.load_file(Rails.root.join('vendor', 'languages.yml')).each do |_name, details|
lib/gitlab/repo_path.rb:      Gitlab::GlRepository.types.each do |_name, type|
lib/gitlab/database/load_balancing/configuration.rb:          config.service_discovery.each do |key, _|
lib/gitlab/seeder.rb:      Gitlab::Database.database_base_models.each do |_, model|
app/graphql/types/commit_signatures/verification_status_enum.rb:      ::CommitSignatures::GpgSignature.verification_statuses.each do |status, _|
app/services/packages/debian/process_package_file_service.rb:        file_metadata[:files].each do |_, entry|
app/models/concerns/bulk_insertable_associations.rb:    self.class.reflections.each do |_, reflection|
spec/lib/gitlab/database/migrations/reestablished_connection_stack_spec.rb:    Gitlab::Database.database_base_models_with_gitlab_shared.each do |db_config_name, _|
spec/lib/gitlab/database/load_balancing/setup_spec.rb:      models.each do |_, model|
spec/models/state_note_spec.rb:    ResourceStateEvent.states.each do |state, _value|
spec/models/ci/job_artifact_spec.rb:    described_class.file_types.each do |file_type, _|
spec/models/ci/job_artifact_spec.rb:    described_class.file_types.each do |file_type, _|
spec/models/ci/build_spec.rb:    Ci::JobArtifact.file_types.each do |type, _|
spec/requests/api/project_templates_spec.rb:    TemplateFinder::VENDORED_TEMPLATES.each do |template_type, _|
spec/support/shared_examples/lib/gitlab/database/reestablished_connection_stack_shared_examples.rb:    Gitlab::Database.database_base_models.each do |_, model_class|
spec/support/helpers/database/multiple_databases_helpers.rb:      Gitlab::Database.database_base_models.each do |_, base_model|
spec/support/helpers/repo_helpers.rb:    files.each do |filename, _content|
doc/development/database/efficient_in_operator_queries.md:records_by_id.each do |id, _|
spec/features/commits_spec.rb:      commits.chunk { |c| c.committed_date.in_time_zone.to_date }.each do |day, _daily_commits|
spec/config/settings_spec.rb:      described_class.repositories.storages.each do |_, storage|
qa/qa/specs/features/api/3_create/repository/project_archive_compare_spec.rb:        users.each do |_, user_info|
qa/qa/specs/features/ee/browser_ui/10_govern/change_vulnerability_status_spec.rb:          vulnerabilities.each do |name, _description|
qa/spec/specs/runner_spec.rb:          QA::Runtime::Env.supported_features.each do |tag, _|
qa/spec/specs/runner_spec.rb:          QA::Runtime::Env.supported_features.each do |tag, _|
tooling/danger/analytics_instrumentation.rb:          helper.changed_lines(file_name).each do |mod_line, _i|
ee/lib/gitlab/graphql/aggregations/epics/lazy_epic_aggregate.rb:            tree.each do |_, node|
ee/lib/remote_development/workspaces/create/post_flatten_devfile_validator.rb:          variables.each do |variable, _|
ee/lib/gitlab/code_owners/file.rb:        parsed_data.each do |_, section_entries|
ee/app/services/elastic/process_bookkeeping_service.rb:      specs.each do |spec, _|
ee/app/services/security/security_orchestration_policies/ci_configuration_service.rb:        ci_configuration.each do |_, job_configuration|
ee/spec/lib/gitlab/usage/metrics/instrumentations/count_security_scans_metric_spec.rb:      ::Security::Scan.scan_types.except('cluster_image_scanning').each do |name, _|
ee/spec/lib/gitlab/usage/metrics/instrumentations/count_secure_pipelines_metric_spec.rb:      ::Security::Scan.scan_types.except('cluster_image_scanning').each do |name, _|
ee/spec/lib/gitlab/usage/metrics/instrumentations/count_secure_pipelines_metric_spec.rb:    ::Security::Scan.scan_types.except('cluster_image_scanning').each do |name, _|
ee/spec/lib/ee/gitlab/elastic/helper_spec.rb:      @indices.each do |index_name, _|
ee/spec/models/ee/namespace_spec.rb:        limits.each do |_attribute, limit|
ee/spec/models/vulnerabilities/feedback_spec.rb:      described_class.categories.each do |category, _|
ee/spec/models/package_metadata/sync_configuration_spec.rb:    ::Enums::Sbom::PURL_TYPES.each do |purl_type, _|
ee/spec/requests/api/graphql/mutations/member_role/create_member_role_spec.rb:    MemberRole::ALL_CUSTOMIZABLE_PERMISSIONS.each do |permission, _options|
ee/spec/controllers/projects_controller_spec.rb:          params.each do |param, _value|
ee/spec/services/approval_rules/finalize_service_spec.rb:              expected_rules.each do |_key, hash|
ee/spec/services/approval_rules/finalize_service_spec.rb:              expected_rules.each do |_key, hash|
ee/spec/services/approval_rules/finalize_service_spec.rb:        ApprovalProjectRule.rule_types.except(:code_owner, :report_approver).each do |rule_type, _value|
ee/spec/services/package_metadata/sync_service_spec.rb:        ::Enums::PackageMetadata.purl_types.each do |purl_type, _|