Implement LDAP authentication

Reviewers: teon.banek

Reviewed By: teon.banek

Subscribers: pullbot

Differential Revision: https://phabricator.memgraph.io/D1888

src/auth/auth.hpp

@@ -10,6 +10,14 @@
 
 namespace auth {
 
+/**
+ * Call this function in each `main` file that uses the Auth stack. It is used
+ * to initialize all libraries (primarily OpenLDAP).
+ *
+ * NOTE: This function must be called **exactly** once.
+ */
+void Init();
+
 /**
  * This class serves as the main Authentication/Authorization storage.
  * It provides functions for managing Users, Roles and Permissions.