windows provisioning: automatically choose the right hash algorithm

...based on the length of the given hash.

Additionally use -ine for string comparison, which explicitly does
case-insensitive comparison. That is what the function needs, previously
it was done implicitly by -ne.

And remove MD5, it's not used anywhere.

Pick-to: 6.10 6.8 6.5
Change-Id: Ib4303737e5e1d743dd0be1a8f829be9a0db2bc04
Reviewed-by: Tero Heikkinen <tero.heikkinen@qt.io>
(cherry picked from commit e5e813ef90)

coin/provisioning/common/windows/helpers.ps1

@@ -2,16 +2,20 @@ function Verify-Checksum
 {
     Param (
         [string]$File=$(throw("You must specify a filename to get the checksum of.")),
-        [string]$Expected=$(throw("Checksum required")),
-        [ValidateSet("sha256","sha1","md5")][string]$Algorithm="sha1"
+        [string]$Expected=$(throw("Checksum required"))
     )
+    switch ($Expected.Length) {
+        40 { $Algorithm = "SHA1" }
+        64 { $Algorithm = "SHA256" }
+        default { throw "Unknown hash length for: $Expected" }
+    }
     Write-Host "Verifying checksum of $File"
     $fs = new-object System.IO.FileStream $File, "Open"
     $algo = [type]"System.Security.Cryptography.$Algorithm"
     $crypto = $algo::Create()
     $hash = [BitConverter]::ToString($crypto.ComputeHash($fs)).Replace("-", "")
     $fs.Close()
-    if ($hash -ne $Expected) {
+    if ($hash -ine $Expected) {
         throw "Checksum verification failed, got: '$hash' expected: '$Expected'"
     }
 }