fix testbreak with SSH_ASKPASS change (#394)

Added askpass utility to support change around SSH_ASKPASS logic. Since prompt is now passed as a commandline parameter to SSH_ASKPASS, "cmd /c echo" based logic no longer works for automated passing of password.

contrib/win32/openssh/OpenSSHTestHelper.psm1

@@ -345,10 +345,13 @@ function Get-LocalUserProfile
     if (-not (Test-Path $userProfileRegistry) ) {        
         #create profile
         if (-not($env:DISPLAY)) { $env:DISPLAY = 1 }
-        $env:SSH_ASKPASS="$($env:ComSpec) /c echo $($OpenSSHTestAccountsPassword)"
+        $askpass_util = Join-Path $Script:E2ETestDirectory "utilities\askpass_util\askpass_util.exe"
+        $env:SSH_ASKPASS=$askpass_util
+        $env:ASKPASS_PASSWORD=$OpenSSHTestAccountsPassword
         $ret = ssh -p 47002 "$User@localhost" echo %userprofile%
         if ($env:DISPLAY -eq 1) { Remove-Item env:\DISPLAY }
         remove-item "env:SSH_ASKPASS" -ErrorAction SilentlyContinue
+        Remove-item "env:ASKPASS_PASSWORD" -ErrorAction SilentlyContinue 
     }   
     
     (Get-ItemProperty -Path $userProfileRegistry -Name 'ProfileImagePath').ProfileImagePath    

regress/pesterTests/CommonUtils.psm1

@@ -97,7 +97,9 @@ function Add-PasswordSetting
     $platform = Get-Platform
     if ($platform -eq [PlatformType]::Windows) {
         if (-not($env:DISPLAY)) {$env:DISPLAY = 1}
-        $env:SSH_ASKPASS="cmd.exe /c echo $pass"
+        $askpass_util = Join-Path $PSScriptRoot "utilities\askpass_util\askpass_util.exe"
+        $env:SSH_ASKPASS=$askpass_util
+        $env:ASKPASS_PASSWORD=$pass
     }
 }
 
@@ -105,6 +107,7 @@ function Remove-PasswordSetting
 {
     if ($env:DISPLAY -eq 1) { Remove-Item env:\DISPLAY }
     Remove-item "env:SSH_ASKPASS" -ErrorAction SilentlyContinue
+    Remove-item "env:ASKPASS_PASSWORD" -ErrorAction SilentlyContinue
 }
 
 $Taskfolder = "\OpenSSHTestTasks\"

regress/pesterTests/utilities/askpass_util/README.txt

@@ -0,0 +1,3 @@
+askpass_util is a test utility to be used in conjunction with SSH_ASKPASS in ssh. 
+
+It simply spits out environment variable stored in ASKPASS_PASSWORD.

regress/pesterTests/utilities/askpass_util/askpass_util.cpp

@@ -0,0 +1,13 @@
+// askpass_util.cpp : Defines the entry point for the console application.
+//
+
+#include <Windows.h>
+#include <stdio.h>
+
+int main()
+{
+	//read from environment variable, spit it out on stdout
+	printf("%s", getenv("ASKPASS_PASSWORD"));
+	return 0;
+}
+