[FEATURE] Support 'format' parameter in the export command

[RuiRomano]

Use Case / Problem

I want to export item definition using the format parameter available in Fabric Get Definition: https://learn.microsoft.com/en-us/rest/api/fabric/semanticmodel/items/get-semantic-model-definition?tabs=HTTP#uri-parameters

Proposed Solution

New parameter in the export command: format

Alternatives Considered

Call the fabric api command, but requires me to handle the 202 return code which is not easy.

Impact Assessment

• This would help me personally
• This would help my team/organization
• This would help the broader fabric-cli community
• This aligns with Microsoft Fabric roadmap items

Implementation Attestation

• I understand this feature should maintain backward compatibility with existing commands
• I confirm this feature request does not introduce performance regressions for existing workflows
• I acknowledge that new features must follow fabric-cli's established patterns and conventions

Implementation Notes

No response

[HasanAboShally]

/help-wanted
Thanks @RuiRomano! this is a great suggestion and also aligns with #24. We plan to implement it 👍

[microsoft-github-policy-service]

This issue has been marked as help wanted.
Community contributions are welcome and appreciated.