Chore: storybook improvements

[hellofanny]

Ported from https://github.com/vtex-sites/nextjs.store/pull/129

What's the purpose of this pull request?

General improvements on Storybook.

How does it work?

• Displays the Sandbox tab: so we can test viewports and use other addons (Accessibility)
• Adds project's viewports to help with components' resizes tests
  
• Fixes some console errors:
  - Importing from '@storybook/addon-docs/blocks' is deprecated.
  - Adds OnChange handler to components examples (Checkbox, Radio, Toggle)
  

How to test it?

• Check on the preview if Sandbox and Docs tabs are available (except Getting Started, Theming, Fundamentals pages and Changelog)
• When switching tabs, Sandbox might not be working properly until you reload the page.
  There is a note on the Getting Started's page regarding this issue
  

References

• Canvas tab not working properly until after reload when using --docs flag.
• Viewport Addon
• configure tabs: title, visibility, order and disable storybookjs/storybook#9095

Checklist

You may erase this after checking them all ;)

Changelog

• Added an entry in the CHANGELOG.md at the beginning of its due section. The latest version should comes first.
• Added the PR number with the PR link at the entry in the CHANGELOG.md. E.g., New items in the pull_request_template.md (#12)

PR Description

• Added a label according to the PR goal - Breaking change, Enhancement, Bug or Chore.
• Added the component, hook, or pathname in-between backticks (``) - If applicable. E.g., ComponentName component.
• Identified the function or parameter in the PR - If applicable. E.g., useWindowDimensions hook.

Documentation

• PR description
• Added to/Updated the Storybook - if applicable.
• For documentation changes, ping @ carolinamenezes, @ PedroAntunesCosta or @ Mariana-Caetano to review and update.

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Name	Status	Preview	Updated
gatsby-store-storybook	✅ Ready (Inspect)	Visit Preview	Jun 20, 2022 at 1:54PM (UTC)

[vtex-sites]

Preview is ready

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👀   Preview: https://sfj-62679bd--gatsby.preview.vtex.app
🔬   Go deeper by inspecting the Build Logs
📝   based on commit 62679bd

[renatamottam]

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[vtex-sites]

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