[JENKINS-55787] Switch labels from entry to checkbox

[jsoref]

JENKINS-55787 - Use checkbox for labels, not entry

Basically checkboxes should have labels, splitting the labels away from their checkboxes is poor UX, poor accessibility. This change brings the layout more inline with how normal settings UIs lay out checkboxes.

This supersedes #675

Checklist

• I have read the CONTRIBUTING doc
• I have referenced the Jira issue related to my changes in one or more commit messages
• Unit tests pass locally with my changes
• No Javadoc warnings were introduced with my changes
• No findbugs warnings were introduced with my changes
• I have interactively tested my changes
• Any dependent changes have been merged and published in upstream modules (like git-client-plugin)

Types of changes

• Bug fix - Non-breaking change which fixes an issue