ci: Add scripts to provide WiX 4 package on Windows

Run `.gitlab/ci/repackage/wix.ps1` with `-version 4.0.4`
and host the package file ourselves.

.gitlab/.gitignore

@@ -22,5 +22,6 @@
 /unstable-jom*
 /watcom
 /wix3
+/wix4
 /clang-tidy-fixes
 /num_warnings.txt

.gitlab/ci/wix4.ps1

@@ -0,0 +1,20 @@
+$erroractionpreference = "stop"
+
+$version = "4.0.4"
+$sha256sum = "FB6E94C89B12FB65D3AA0CF9E9C630DAFCC7D57F1E66C7D6035CAD37A38CC284"
+$filename = "wix-$version-win-any-1"
+$tarball = "$filename.zip"
+
+$outdir = $pwd.Path
+$outdir = "$outdir\.gitlab"
+$ProgressPreference = 'SilentlyContinue'
+Invoke-WebRequest -Uri "https://cmake.org/files/dependencies/$tarball" -OutFile "$outdir\$tarball"
+$hash = Get-FileHash "$outdir\$tarball" -Algorithm SHA256
+if ($hash.Hash -ne $sha256sum) {
+    exit 1
+}
+
+Add-Type -AssemblyName System.IO.Compression.FileSystem
+[System.IO.Compression.ZipFile]::ExtractToDirectory("$outdir\$tarball", "$outdir")
+Move-Item -Path "$outdir\$filename" -Destination "$outdir\wix4"
+Remove-Item "$outdir\$tarball"