Add Powershell version of fetch configlet script

bin/fetch-configlet.ps1

@@ -0,0 +1,24 @@
+Function DownloadUrl ([string] $FileName, $Headers) {
+    $latestUrl = "https://api.github.com/repos/exercism/configlet/releases/latest"
+    $json = Invoke-RestMethod -Headers $Headers -Uri $latestUrl
+    $json.assets | Where-Object { $_.browser_download_url -match $FileName } | Select-Object -ExpandProperty browser_download_url
+}
+
+Function Headers {
+    If ($GITHUB_TOKEN) { @{ Authorization = "Bearer ${GITHUB_TOKEN}" } } Else { @{ } }
+}
+
+Function Arch {
+    If ([Environment]::Is64BitOperatingSystem) { "64bit" } Else { "32bit" }
+}
+
+$arch = Arch
+$headers = Headers
+$fileName = "configlet-windows-$arch.zip"
+$outputDirectory = "bin"
+$outputFile = Join-Path -Path $outputDirectory -ChildPath $fileName
+$zipUrl = DownloadUrl -FileName $fileName -Headers $headers
+
+Invoke-WebRequest -Headers $headers -Uri $zipUrl -OutFile $outputFile
+Expand-Archive $outputFile -DestinationPath $outputDirectory -Force
+Remove-Item -Path $outputFile