fixes for front end saml work and to align with data requirements.

...ps/third_party_auth/migrations/0002_auto_20200721_1650.py

common/djangoapps/third_party_auth/models.py

..._auth/samlproviderconfig/tests/test_samlproviderconfig.py

...n/djangoapps/third_party_auth/samlproviderconfig/views.py

...arty_auth/samlproviderdata/tests/test_samlproviderdata.py

common/djangoapps/third_party_auth/samlproviderdata/views.py

.../djangoapps/third_party_auth/tests/specs/test_testshib.py

...re/djangoapps/user_authn/views/tests/test_logistration.py