Propagates Covered Experience context to Sidekiq Workers

The covered experience will start and trigger a background job. While we can infer most of the context in a synchronous manner, we must propagate it to support async next step(s).

Here's a high-level implementation example:

experience = Labkit::CoveredExperience.start
do_some_stuff
experience.checkpoint
Worker.perform_async

class Worker
  def perform
    Labkit::CoveredExperience.resume do |covered_experience|
      # do work
    end
  end
end