[Windows] Refactor virtual-env image generation provisioners (#1288)

* refactor virtual-env image generation provisioners

images/win/scripts/ImageHelpers/VisualStudioHelpers.ps1

@@ -0,0 +1,76 @@
+Function Install-VisualStudio
+{
+    <#
+    .SYNOPSIS
+        A helper function to install Visual Studio.
+
+    .DESCRIPTION
+        Prepare system environment, and install Visual Studio bootstrapper with selected workloads.
+
+    .PARAMETER BootstrapperUrl
+        The URL from which the bootstrapper will be downloaded. Required parameter.
+
+    .PARAMETER WorkLoads
+        The string that contain workloads that will be passed to the installer.
+    #>
+
+    Param
+    (
+        [Parameter(Mandatory)]
+        [String] $BootstrapperUrl,
+        [String] $WorkLoads
+    )
+
+    Write-Host "Downloading Bootstrapper ..."
+    $BootstrapperName = [IO.Path]::GetFileName($BootstrapperUrl)
+    $bootstrapperFilePath = Start-DownloadWithRetry -Url $BootstrapperUrl -Name $BootstrapperName
+
+    try
+    {
+        Write-Host "Enable short name support on Windows needed for Xamarin Android AOT, defaults appear to have been changed in Azure VMs"
+        $shortNameEnableProcess = Start-Process -FilePath fsutil.exe -ArgumentList ('8dot3name', 'set', '0') -Wait -PassThru
+
+        $shortNameEnableExitCode = $shortNameEnableProcess.ExitCode
+        if ($shortNameEnableExitCode -ne 0)
+        {
+            Write-Host "Enabling short name support on Windows failed. This needs to be enabled prior to VS 2017 install for Xamarin Andriod AOT to work."
+            exit $shortNameEnableExitCode
+        }
+
+        Write-Host "Starting Install ..."
+        $bootstrapperArgumentList = ('/c', $bootstrapperFilePath, $WorkLoads, '--quiet', '--norestart', '--wait', '--nocache' )
+        $process = Start-Process -FilePath cmd.exe -ArgumentList $bootstrapperArgumentList -Wait -PassThru
+
+        $exitCode = $process.ExitCode
+        if ($exitCode -eq 0 -or $exitCode -eq 3010)
+        {
+            Write-Host "Installation successful"
+            return $exitCode
+        }
+        else
+        {
+            Write-Host "Non zero exit code returned by the installation process : $exitCode"
+            exit $exitCode
+        }
+    }
+    catch
+    {
+        Write-Host "Failed to install Visual Studio; $($_.Exception.Message)"
+        exit -1
+    }
+}
+
+function Get-VsCatalogJsonPath {
+    $instanceFolder = Get-Item "C:\ProgramData\Microsoft\VisualStudio\Packages\_Instances\*" | Select-Object -First 1
+    return Join-Path $instanceFolder.FullName "catalog.json"
+}
+
+function Get-VisualStudioPath {
+    return (Get-VSSetupInstance | Select-VSSetupInstance -Product *).InstallationPath
+}
+
+function Get-VisualStudioComponents {
+    $vsPackages = (Get-VSSetupInstance | Select-VSSetupInstance -Product *).Packages.Id
+    $vsPackages  | Select-Object @{n = 'Package'; e = {$_}} |
+    Where-Object { $_.Package -notmatch "[0-9a-fA-F]{8}\-[0-9a-fA-F]{4}\-[0-9a-fA-F]{4}\-[0-9a-fA-F]{4}\-[0-9a-fA-F]{12}" }
+}