Add Windows platform check and refactor structure definitions in azex…

[ereli-sevenai]

This PR introduces a crucial check to ensure the azext_ssh module runs only on Windows platforms, preventing import errors on non-Windows systems.

[azure-client-tools-bot-prd]

️✔️Azure CLI Extensions Breaking Change Test

️✔️Non Breaking Changes

[azure-client-tools-bot-prd]

Hi @ereli-okami,
Please write the description of changes which can be perceived by customers into HISTORY.rst.
If you want to release a new extension version, please update the version in setup.py as well.

[azure-client-tools-bot-prd]

Hi @ereli-okami,
Since the current milestone time is less than 7 days, this pr will be reviewed in the next milestone.

[microsoft-github-policy-service]

Thank you for your contribution ereli-okami! We will review the pull request and get back to you soon.

[yonzhan]

Thank you for your contribution! We will review the pull request and get back to you soon.

[ereli-sevenai]

@microsoft-github-policy-service agree [company="Okami AI"]

[ereli-sevenai]

@microsoft-github-policy-service agree company="Okami AI"

[github-actions]

⚠️ Suggestions

Module: ssh

• Update version to 2.0.4 in setup.py

Notes

• Stable/preview tag is inherited from last release. If needed, please add stable/preview label to modify it.
• Major/minor/patch/pre increment of version number is calculated by pull request code changes automatically. If needed, please add major/minor/patch/pre label to adjust it.
• For more info about extension versioning, please refer to Extension version schema