[Windows] Install vsix extensions using CDN endpoint (#3244)

* Install extensions for VS19

* Get vsix packages name in runtime

* add a bit of debug

* Get extension id from the marketplace uri

* Add extension name

* skip vcredist installation

* Add Get-VsixExtenstionFromMarketplace to ImageHelpers.psm1

* Fix DownloadUri name in the function

* DownloadUri in lower case

* Add packages to the readme

* Add a condition to software report

* fix spelling in function

* Simplify toolset + get rid of backticks

images/win/scripts/Tests/Vsix.Tests.ps1

@@ -3,9 +3,16 @@ Describe "Vsix" {
     $requiredVsixs = $toolset.visualStudio.vsix
 
     $allPackages = (Get-VSSetupInstance | Select-VsSetupInstance -Product *).Packages
-    $testCases = $requiredVsixs | ForEach-Object { @{ VsixId = $_.Id;  AllPackages = $allPackages }}
+    $testCases = $requiredVsixs | ForEach-Object {
+        $vsix = Get-VsixExtenstionFromMarketplace -ExtensionMarketPlaceName $_
+        @{
+            VsixName = $vsix.ExtensionName
+            VsixId = $vsix.VsixId
+            AllPackages = $allPackages
+        }
+    }
     if ($testCases.Count -gt 0) {
-        It "Extension <VsixId>" -TestCases $testCases {
+        It "Extension <VsixName> is installed" -TestCases $testCases {
             $objVsix = $AllPackages | Where-Object { $_.id -eq $VsixId }
             $objVsix | Should -Not -BeNullOrEmpty
         }