* Adjust JWT and SAML fetch-and-update user to save new attributes

Before this change, JWT/SAML logins would attempt to update attributes, but never considered the first-name or
last-name attributes.

* Attempts to fix tests to prevent pulluting test users with "Unknown"

* No deleting users.

* Unit tests checking that first/last names are updated for SSO users

When an SSO user is first logged in, they might not have first_name and/or last_name keys. This is allowed, but the
names will be "Unknown" in the app-db. Subsequently, a User may log in again with SSO but have fisrt/last name
attributes, which should update the Metabase user data in the app-db.

These unit tests set up such a scenario to check that the :first_name and :last_name keys are indeed updated.

* Adjust Enterprise LDAP to also use SSO-UTILS

Trying to unify the LDAP implementation with JWT/SAML a bit here.

* Lint error

* Reverting LDAP n...