feat[dev]: ✨ implement A11y improvements for Flag Template

[yoezlem]

Description

This task describes the Storybook implementation for the Flag template as part of the A11y improvements outlined in Epic #1465.

A11y improvements for the Flag template can be found here: Flag Notes.

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Comment

See @sd-flag

Additional Information

• Before working on this template ticket, please finish the main component ticket first. This template ticket is linked to the component and will be resolved once the component's A11y improvements are completed:
  feat[dev]: ✨ implement A11y improvements to sd-flag #1611

DoR

• Item has been estimated by the team
• Item dependencies have been identified and documented

DoD

• Documentation has been created/updated (if applicable)
• Migration Guide has been created/updated (if applicable)
• Relevant E2E tests (Features, A11y, Bug fixes) are created/updated
• Relevant stories (Features, A11y) are created/updated
• Implementation works successfully on feature branch