[RFE] Allow for dynamic whitelist

[GerbenWelter]

IMO one of the main reasons OpenShift admins develop custom tooling for group sync is the need to sync from a whitelist. The LDAP evironment I currently have to use requires the augmented AD configuration and additionally the LDAP_MATCHING_RULE_IN_CHAIN rule for finding the group members. This makes it requires the use of a whitelist.

What I would like to have is that the whitelist can be kept in a separate ConfigMap that can be managed by another CronJob or that the operator can build the whitelist dynamically based on an LDAP filter or some regular expression.

[ocpvkb]

LDAP filter or some regular expression +1