When a job is added to Sidekiq by ActiveJob, make sure we still can get the
original job_id provider by Sidekiq. We do this by adding the sidekiq jid to
provider_job_id field on the job object.

Partly fixes #18821
Signed-off-by: NJeroen van Baarsen <jeroenvanbaarsen@gmail.com>

When queueing with DelayedJob, get the id of the job instance and report
it back to ActiveJob as provider_job_id.

* Jobs generated now inherent from ApplicationJob
* ApplicationJob inherents from ActiveJob::Base
* Added entry to changelog
Signed-off-by: NJeroen van Baarsen <jeroenvanbaarsen@gmail.com>

type.

This allows specific jobs to be tested, while preventing others from
being performed unnecessarily.

Example:

    def test_hello_job
      assert_performed_jobs 1, only: HelloJob do
        HelloJob.perform_later('jeremy')
        LoggingJob.perform_later
      end
    end

An array may also be specified, to support testing multiple jobs.

Example:

    def test_hello_and_logging_jobs
      assert_nothing_raised do
        assert_performed_jobs 2, only: [HelloJob, LoggingJob] do
          HelloJob.perform_later('jeremy')
          LoggingJob.perform_later('stewie')
          RescueJob.perform_later('david')
        end
      end
    end

Fixes #18802.

Trim space and document :only option.

Unfortunately, the HashWithIndifferent access approach is insufficient
for our needs. It's perfectly reasonable to want to use keyword
arguments with Active Job, which we will see as a symbol keyed hash. For
Ruby to convert this back to keyword arguments, it must deserialize to a
symbol keyed hash.

There are two primary changes to the serialization behavior. We first
treat a HWIA separately, and mark it as such so we can convert it back
into a HWIA during deserialization.

For normal hashes, we keep a list of all symbol keys, and convert them
back to symbol keys after deserialization.

Fixes #18741.

With the option, assert_enqueued_jobs will check the number of times a specific kind of job is enqueued.

Indent the list content by 4 spaces instead of 2 to match the other
changelog files. Also wrap the lines around 80 chars.

Finally update the documentation example with nit-picky things.

We will support only Ruby >= 2.1.

But right now we don't accept pull requests with syntax changes to drop
support to Ruby 1.9.