Implement unit tests for auth-gen-token

Implement unit tests for auth-gen-token

The unit test is breaking the 80 char limit in some places
but the remaining lines it breaks the limit I feel
forcing the 80 char limit will impair readibility

Patch V2: adapt unit tests to other V2 patches
Patch V4: Resolve rebase conflicts
Patch V5: Add \ lost in rebase that broke compilation
Patch V7: Fix unit test failure, try to stay below 80
Acked-by: David Sommerseth <davids@openvpn.net>
Message-Id: <20190917123321.15993-1-arne@rfc2549.org>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg18821.html

Signed-off-by: Gert Doering <gert@greenie.muc.de>