feat: Enhance the `label` property in `CheckboxField` to be of the type `React.ReactNode`

[rfgamaral]

Short description

This change enhances the label property in the CheckboxField component to be of the type React.ReactNode, allowing one to use a React component as label, instead of only a string.

This will permit that the checkbox, icon, and text label, in the items such as the ones below, are all clickable (thus toggling the check state on and off):

PR Checklist

• [x] Added tests for bugs / new features
• [x] Updated docs (storybooks, readme)
• [x] Executed npm run validate and made sure no errors / warnings were shown
• [x] Described changes in CHANGELOG.md
• [ ] Bumped version in package.json and package-lock.json (npm --no-git-tag-version version <major|minor|patch>) ref
• [ ] Updated all static build artifacts (npm run build-all)

Versioning

Minor: v15.1.0

[rfgamaral]

cc @gnapse, this follows-up our conversation over DM on Twist