dbworker: Set additional columns in MarkCompleted/MarkErrored

Created by: mrnugget

It would be nice if it was possible to set additional columns when a record is MarkCompleted/MarkErrored.

For example: in campaigns we want to set the updated_at column every time a changeset has been updated.

That could also be done by

• Defining our own MarkCompleted/MarkErrored methods on a dbworker.Store shim
• Setting up a database trigger
• Defining a database view that does a max(updated_at, finished_at, started_at)
• ...

But maybe there's a more ergonomic way.