Update Update Az.DesktopVirtualization module.ps1

[aaronparker]

• Addresses Script uses Write-Output instead of Write-Host #46 - replaces Write-Output with Write-Host to ensure the Install-AutomationModule function doesn't return unexpected data
• Also updates:
  • Explanation of the script
  • Uses splatting with New-AzAutomationModule for better readability
  • Updates consistent argument usage for Invoke-RestMethod