When a user now logs in for the first time for any external auth (LDAP, JWT, Keystone, Github, Google, Dex), they will be presented with a confirmation screen that affords them the opportunity to change their Quay-assigned username.
Addresses most of the user issues around #74
Before this change, external auth such as Keystone would fail if a user without an email address tried to login, even if the email feature was disabled.
It appears the recent migration of the LDAP code and add of a check for the admin username/password being invalid *broke the LDAP password check*, allowing any password to succeed for login. This fixes the problem, add unit tests to verify the fix and add some tests to our other external auth test suite.
A release will be needed immediately along with an announcement
Fixes two issues found with our LDAP handling code. First, we now follow referrals in both LDAP calls, as some LDAP systems will return a referral instead of the original record. Second, we now make sure to handle multiple search result pairs properly by further filtering based on the presence of the 'mail' attribute when we have multiple valid pairs. This CL also adds tests for all of the above cases.
Currently, we use the Quay username via `verify_user` when we go to create the encrypted password. This is only correct if Quay has not generated its own different username for the LDAP user, and fails if it has. We therefore add a new method `confirm_existing_user`, which looks up the federated login for the LDAP user and then runs the auth flow using that username.
