Better support for ActiveJob::Continuable #3120

Continuable jobs (Rails 8.1) already produce one queue.process transaction per execution, linked in one trace, which matches the queues spec. Improve on that without changing it:

• add continuation info (resumptions, steps) to transactions and errors
• report errors that Rails turns into resumptions, when active_job_report_on_retry_error is enabled

Depends on #3116