Unified ldap_initialize() function

Replace all ldap.initialize() calls with a helper function
ldap_initialize(). It handles cacert and cert validation correctly. It
also provides a unique place to handle python-ldap 3.0 bytes warnings in
the future.

Fixes: https://pagure.io/freeipa/issue/7411
Signed-off-by: Christian Heimes <cheimes@redhat.com>
Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>

ipaserver/secrets/common.py

@@ -4,6 +4,8 @@ import ldap
 import ldap.sasl
 import ldap.filter
 
+from ipapython.ipaldap import ldap_initialize
+
 
 class iSecLdap(object):
 
@@ -27,7 +29,7 @@ class iSecLdap(object):
         return self._basedn
 
     def connect(self):
-        conn = ldap.initialize(self.uri)
+        conn = ldap_initialize(self.uri)
         if self.auth_type == 'EXTERNAL':
             auth_tokens = ldap.sasl.external(None)
         elif self.auth_type == 'GSSAPI':