fix(ui5-shellbar): Change path in imports for playground

[ckoutsiaris]

Thank you for your contribution! 👏

Based on this https://github.com/SAP/ui5-webcomponents/blob/bdfeb78d6f0e166e17bc8895f54aac179a7752a0/docs/Migration-guides.md#new-npm-package-ui5webcomponents-fiori

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Pull Request Checklist

• Reviewed the Contributing Guidelines
  • Especially the How to Contribute section
• Correct commit message style

[claassistantio]

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[claassistantio]

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