Keep track of collapsed steps and avoid expanding them automatically

[das7pad]

Fixes #822

Any user action that collapsed steps is persisted now.
This affects the collapsed state when navigating back and forth between
stages and refreshes from the steps polling while the job is running.

Testing done

Details

pipeline {
    agent any

    stages {
        stage('Hello') {
            steps {
                script {
                    for(int i=1; i<=10; i++) {
                        stage("Stage - ${i}") {
                            sh 'for i in 1 2 3; do sleep 1; echo "Slept ${i} times"; done'
                            sh 'for i in 4 5 6; do sleep 1; echo "Slept ${i} times"; done'
                        }
                    }
                }
            }
        }
    }
}

• Trigger a build
• Select a step and collapse it. It does not get re-opened as the build progresses.
• Select a previous stage and collapse the last step. Switch back and forth between another stage, the last step remains collapsed.
• Expand the step again; switch back and forth, the last step is expanded.

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

[lewisbirks]

LGTM! Thanks for the contributions 🚀

[nre-ableton]

Thanks for fixing this, it was driving me crazy 😅 ❤️