Extend delayed_job plugin

[norbertnytko]

It would be great to monitor delayed_job enqueues in case of any errors or latency related to those events.

Example usage:

Datadog.configure do |c|
  c.use :delayed_job, {
    service_name: "some_service_name-delayed_job",
    client_service_name: "some_service_name-delayed_job-client",
    analytics_enabled: true,
  }
end

[marcotc]

Thank you for your contribution, @norbertnytko! The PR looks good. 🚀

[marcotc]

@norbertnytko I noticed you are based off an older branch of the tracer. Could you please rebase it with master instead?

Out of curiosity, we used to guide contributors to base their changes off the latest X.Y-dev branch, which I believe is what you did here. We have since removed that recommendation from our guides. Did you base you changes off 0.28-dev because you found instructions telling you to do such?

The base branch was changed.

[norbertnytko]

@marcotc rebased
Exactly, CONTRIBUTING.md

[ericmustin]

@norbertnytko we've released 0.42.0 with this work, thanks again for the contribution! https://github.com/DataDog/dd-trace-rb/releases/tag/v0.42.0