[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

As part of this Pull Request I have

• Checked for duplicate Pull Requests
• Associated it with relevant GitHub Issues
• Ensured my code/branch is up-to-date with the latest changes in the main branch
• Performed testing and provided evidence.
• Updated relevant and associated documentation.
• Ensure PowerShell module versions have been updated (manually or with the ./tools/Update-ModuleVersions.ps1 script)

[alalvi00]

Good looks