[core] Option to either follow or not LDAP referrals for auth

There have been a few instances where attempting Auth after HUE-1442 has followed referrals. As a result, Hue may try to contact AD servers that are not reachable.

Need to test, but from looking at the code, it seems we only disable referral chasing in:

./apps/useradmin/src/useradmin/ldap_access.py: ldap.set_option(ldap.OPT_REFERRALS, 0)

So we may need to do one of the following:

• Give an option to disable/enable referral chasing.
• Move the disabling of referral chasing to a more global location. If possible.
• Just add "ldap.set_option(ldap.OPT_REFERRALS, 0)" to "desktop/core/src/desktop/auth/backend.py".