Consider findWorstWarningBetween for branches of running builds

[stuartrowe]

Fixes #794.

Use StatusAndTiming#findWorstWarningBetween to inform the status of branches while a build is still running.

Detection of WarningActions in enclosed nodes is the most reliable way to determine a status for stage or parallel branches. Previously StatusAndTiming#findWorstWarningBetween was only considered for completed pipelines.

Testing done

TODO: I will need to implement a test utility to gather the status of stages and parallel branches for a running pipeline. Currently this is only supported in StagesAndParallelBranchesVisitor for completed pipelines.

Submitter checklist

• Make sure you are opening from a topic/feature/bugfix branch (right side) and not your main branch!
• Ensure that the pull request title represents the desired changelog entry
• Please describe what you did
• Link to relevant issues in GitHub or Jira
• Link to relevant pull requests, esp. upstream and downstream changes
• Ensure you have provided tests that demonstrate the feature works or the issue is fixed

[stuartrowe]

Migrated from jenkinsci/pipeline-graph-analysis-plugin#170

[timja]

Looks good, are you planning to add a test for it?

[stuartrowe]

I'm going to try 😄

[timja]

I'm going to try 😄

Wouldn’t you just need to put a milestone in and not pass it until verified?