Allow sandbox swapping in pipeline

On the managed package version of DevOps, if we refreshed our sandboxes, specifically the sandbox that sits in the middle between the work items and production, we'd have the option to swap the sandboxes. This feature does not seem to exist. We shouldn't have to create a new pipeline if we refreshed sandboxes and need to swap them out.

Start by locating the managed-package pipeline configuration and the sandbox that sits between work items and production. Trace how sandboxes are assigned to an existing pipeline and identify whether a swap operation is supported. Done means refreshed sandboxes can be exchanged without creating a new pipeline, with the existing pipeline still usable afterward.

Written by the indexing model from the issue text.