v5.0.0-beta.1

Bug Fixes

• Addon-backgrounds: Fix tool not appearing, or appearing only after a few navigations (#5439)

Maintenance

• UI:Added iframe stories (#5428)
• UI: Broke up Sidebar (ex-nav) and made stories for subcomponents (#5426)
• UI: Improve about/shortcuts stories by passing in onClose as a prop. (#5425)