chocolatey-visualstudio.extension: allow skipping VS Installer update

This may be useful when instaling a fresh instance of a VS product using
a bootstrapper which installs a specific version of the product
(e.g. the 15.0 bootstrappers available from MSDN).

Note that because the 15.0 bootstrapper does not support
--noUpdateInstaller, the package must be instructed not to pass this
parameter to the bootstrapper, by additionally specifying
--no-noUpdateInstaller.

GitHub-Issue: GH-7 GH-8 GH-10 GH-26

chocolatey-visualstudio.extension/extensions/Assert-VSInstallerUpdated.ps1

@@ -12,6 +12,11 @@ function Assert-VSInstallerUpdated
         [switch] $UseInstallChannelUri
     )
 
+    if ($PackageParameters.ContainsKey('noUpdateInstaller'))
+    {
+        Write-Verbose "Skipping update of the VS Installer because --noUpdateInstaller was passed in package parameters"
+    }
+
     $requiredVersionInfo = Get-VSRequiredInstallerVersion -PackageParameters $PackageParameters -ProductReference $productReference -UseInstallChannelUri:$UseInstallChannelUri
     Install-VSInstaller `
         -RequiredInstallerVersion $requiredVersionInfo.Version `