Add tests/fake-juniper-sso-server.py and tests/juniper-sso-auth

@dlenski Hi Dan, I have implemented an Azure SSO unit test. I hope you'll forgive me for writing it as a separate server rather than integrating it with fake-juniper-server.py – I find the process entangled enough as it is and didn't want to muddle it with even more options.

I have also written a fake-tncc.py script for good measure ;-)

I've also included my suggested fix for the problem that OpenConnect currently fills in the TOTP token into the password field.