[Bug Fix] - Handle scenarios when VNETNAME_s column doesn't exist in Compliance table

[singhgss]

Overview/Summary

In scenarios where no VNET exists or all VNETs are excluded, VNETNAME_s understandably doesn't exist. The workbook query should handle such cases. closes #12

This PR fixes/adds/changes/removes

1. Projects 'VNet Name' as empty string when column VNETNAME_s doesn't exist.

Breaking Changes

N/A

Testing Evidence

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• [x] Checked for duplicate Pull Requests
• [x] Associated it with relevant GitHub Issues
• [x] Ensured my code/branch is up-to-date with the latest changes in the main branch
• [x] Performed testing and provided evidence.
• [x] Updated relevant and associated documentation.
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