implement new Download-FileDirectly function to handle downloads

Tools.ps1

@@ -209,6 +209,19 @@ Function Download-File {
     Return $File
 }
 
+# Downloads from the original URL; BITS handles redirects without preliminary web requests.
+# Without -File, the temporary filename comes from the original URL, not its redirect target.
+Function Download-FileDirectly {
+    param(
+        [Parameter(Mandatory=$true,ValueFromPipeline=$true)][string]$URL,
+        [Parameter(Mandatory=$false,ValueFromPipeline=$false)][string]$File
+    )
+    If ( [string]::IsNullOrEmpty($File) ) { $File = '{0}{1}' -f (Get-TempPath), (Split-Path $URL -Leaf) }
+    Try { Start-BitsTransfer -Source $URL -Destination $File -ErrorAction Stop }
+    Catch { Throw "BITS download failed from ${URL} to ${File}: $($_.Exception.Message)" }
+    Return $File
+}
+
 # Upload a file to a LiquidFiles Filedrop and submit its notification message.
 Function Upload-File {
     <#