Slack notifications for recovered pipelines

Description

Slack notification options for pipeline currently include all pipeline jobs regardless of status and only failed jobs. This means that slack channels either get a lot of spam about jobs that worked fine mixed in with failures, or only failures with no indication that they've been resolved.

Proposal

The proposal is to add a new checkbox to the Slack integration configuration allowing notification of a channel when a pipeline has recovered from a failure state.

Links / references