[AIRFLOW-1711] Use ldap3 dict for group membership
[AIRFLOW-1711] Use ldap3 dict for group membership

Certain schemas for group membership return a
string
instead of a list. Instead of using a check we now
use the entries API from ldap3.

Closes #2731 from bolkedebruin/AIRFLOW-1711

(cherry picked from commit abcf1d584c66ab4f0a4c8c2c56c74104d9a50903)
Signed-off-by: Bolke de Bruin <17f52a69a3ba26c79c8a88ef8c1f26312d9cbf0e@xs4all.nl>

Twistbioscience/incubator-airflow,Twistbioscience/incubator-airflow,Twistbioscience/incubator-airflow,Twistbioscience/incubator-airflow