Create anonymizer tool for SAML responses & Kick off test suite

1. Provide a tool that anonymizes SAML response (pretty much anything about IdP and all the PIIs) and rewrites the signature (`cat saml-response.xml | go run cmd/saml-response-anonymizer/main.go > anonymized-saml-response.xml`)
2. Kick of a test suite with SAML response examples, where we ideally call out what's the IdP behind the scenes (OneLogin etc.)