feat(sbb-image): Round option

[thepian]

The aim is to be able to render sbb-image completely round by supplying an attribute.

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• I have read the Contributing Guidelines for this project.
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• I have searched the pull request tracker for a Pull Request (PR) that matches the one I want to submit, without success.

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• Tests for the changes have been added (for bug fixes / features)
• Docs have been reviewed and added / updated if needed (for bug fixes / features)

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Changes

Changes in this pull request:

• Added attribute to make images round

Browsers

I tested the build on the following browsers:

• Firefox Desktop
• Chrome Desktop
• Edge Desktop
• Safari Desktop
• Chrome Mobile
• Safari Mobile

Pull request type

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• Bugfix
• Feature
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no api changes)
• Build related changes
• Documentation content changes
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Does this introduce a breaking change?

• Yes
• No

[kyubisation]

Hello @thepian
Could you please explain the use case?

[kyubisation]

Use case is for profile pictures.
This PR is however missing stories in Storybook.
It will be blocked until we get around to adding the missing stories.

[jeripeierSBB]

Thanks for your contribution. Continued in #2401