Add support for NTLM to the Docker image

[janegilring]

To Reproduce

apt show gss-ntlmssp

Observed Behavior

N: Unable to locate package gss-ntlmssp

Expected behavior

apt show gss-ntlmssp
Package: gss-ntlmssp
Version: 0.7.0-4build3
Priority: optional

It would be useful to have the NTLM package installed for use with PowerShell remoting from Cloud Shell to Windows machines over WSMan.

Additional context

See this issue where the same request was made to the PowerShell Docker image.