build: change how we find the latest VC tools version (#18468)

Apparently, we were using the package containing the CRT _source code_
to determine the version of the tools.

Also apparently, VS does not guarantee that that package has the same
version as the tools package.

We should use the version of the tools package instead.

build/scripts/Set-LatestVCToolsVersion.ps1

@@ -1,6 +1,6 @@
 $VSInstances = ([xml](& 'C:\Program Files (x86)\Microsoft Visual Studio\Installer\vswhere.exe' -latest -requires Microsoft.VisualStudio.Component.VC.Tools.x86.x64 -include packages -format xml))
 $VSPackages = $VSInstances.instances.instance.packages.package
-$LatestVCPackage = ($VSInstances.instances.instance.packages.package | ? { $_.id -eq "Microsoft.VisualCpp.CRT.Source" })
+$LatestVCPackage = ($VSInstances.instances.instance.packages.package | ? { $_.id -eq "Microsoft.VisualCpp.Tools.Core" })
 $LatestVCToolsVersion = $LatestVCPackage.version;
 
 Write-Output "Latest VCToolsVersion: $LatestVCToolsVersion"