fix: APPS-2648 Fix BannerFeatured error in FlexibleBlock component

[tinuola]

Connected to APPS-2648

Notes:

• Add checks when parsing bylines in FlexibleBannerFeatured to determine if byline arrays exist
• Added test banner data to "divider-between-white-block" FlexibleBlock story

Checklist:

• [x] I checked that it is working locally in the dev server
• [x] I checked that it is working locally in the storybook
• [ ] I checked that it is working locally in the library-website-nuxt dev server
• [x] I added a screenshot of it working
• [ ] UX has reviewed and approved this
• [x] I assigned this PR to someone on the dev team to review
• [x] I used a conventional commit message
• [x] I assigned myself to this PR

[github-actions[bot]]

🚀 Deployed on https://deploy-preview-506--ucla-library-storybook-vue3x.netlify.app

[pghorpade]

:tada: This PR is included in version 2.39.0-alpha.76 :tada:

The release is available on:

• npm package (@alpha dist-tag)
• GitHub release

Your semantic-release bot :package::rocket: