ipatests: new tests for establishing one-way AD trust with shared secret
    
    Tests added for two scenarios:
    1) adding one-way external trust, trust on Windows side is created using
       netdom utility.
    2) adding one-way forest trust, trust on Windows side is created using
       powershell bindings to .Net functions
    Tests verify that specified trusts can be established, trust domains can
    be  fetched and AD user data can be queried by IPA client.
    
    Relates: https://pagure.io/freeipa/issue/6077
    Reviewed-By: Kaleemullah Siddiqui <ksiddiqu@redhat.com>
    Reviewed-By: Kaleemullah Siddiqui <ksiddiqu@localhost.localdomain>