Fold core/extended status modules to reduce nesting

lib/gitlab/ci/status/canceled.rb

lib/gitlab/ci/status/core.rb

lib/gitlab/ci/status/created.rb

lib/gitlab/ci/status/extended.rb

lib/gitlab/ci/status/factory.rb

lib/gitlab/ci/status/failed.rb

lib/gitlab/ci/status/pending.rb

lib/gitlab/ci/status/pipeline/common.rb

lib/gitlab/ci/status/pipeline/success_with_warnings.rb

lib/gitlab/ci/status/running.rb

lib/gitlab/ci/status/skipped.rb

lib/gitlab/ci/status/success.rb

spec/lib/gitlab/ci/status/canceled_spec.rb

spec/lib/gitlab/ci/status/created_spec.rb

spec/lib/gitlab/ci/status/extended_spec.rb

spec/lib/gitlab/ci/status/factory_spec.rb

spec/lib/gitlab/ci/status/failed_spec.rb

spec/lib/gitlab/ci/status/pending_spec.rb

spec/lib/gitlab/ci/status/pipeline/common_spec.rb

...b/gitlab/ci/status/pipeline/success_with_warnings_spec.rb