#5315

Driving this change with tests had some pain points. We decided to work
outside-in, starting with an ATC integration test. It was difficult to
move from the outer TDD loop to the inner - I was surprised by the
number of seemingly-far-flung changes that were required to move from
one failure to the next. These included:

* adding an entry to the auditor to overcome a panic
* modifying the `atc/api/present` package to link the DB entity to the
  API entity

both of these things feel so easy to forget, and it might be nice if
they could be described by a change in the same part of the codebase.

Signed-off-by: Jamie Klassen <cklassen@pivotal.io>
Co-authored-by: Bishoy Youssef <byoussef@pivotal.io>
Co-authored-by: Aidan Oldershaw <aoldershaw@pivotal.io>

#5315 - as per
#5346 (comment),
the ability to archive pipelines is now behind an api flag
`enable-archive-pipeline`.

Signed-off-by: Aidan Oldershaw <aoldershaw@pivotal.io>
Co-authored-by: James Thomson <jthomson@pivotal.io>

Not sure how that got in there!

Signed-off-by: Aidan Oldershaw <aoldershaw@pivotal.io>

Specifically for the pipelines/:pipeline_name/archive endpoint

Signed-off-by: Bishoy Youssef <byoussef@pivotal.io>
Co-authored-by: Taylor Silva <tsilva@pivotal.io>