WIP: Add JS tests of access, login, register, and password reset views
Merge pull request #5682 from edx/renzo/add-js-tests

WIP: Add JS tests of access, login, register, and password reset views
Integrate third party auth into the combined login/registration page.

Change third party auth login failure code to a 401, to detect authentication
success with no linked account.

If already authenticated, redirect immediately to the dashboard.

Use "Location" header correctly for 302 redirects from student views.

Add utility functions for simulating a running third-party auth pipeline.

Add a utility function for checking whether third party auth is enabled.