[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/ImageHelpers/ImageHelpers.psm1

@@ -21,6 +21,7 @@ Export-ModuleMember -Function @(
     'Stop-SvcWithErrHandling'
     'Set-SvcWithErrHandling'
     'Start-DownloadWithRetry'
+    'Get-VsixExtenstionFromMarketplace'
     'Install-VsixExtension'
     'Get-VSExtensionVersion'
     'Get-WinVersion'