Bug 244229 - targetattr not verified against schema when setting an aci
    
    https://bugzilla.redhat.com/show_bug.cgi?id=244229
    
    Description:
    1. When acl contains targetattr keyword:
       (targetattr [!]= "attribute_1 || attribute_2 ...|| attribute_n"),
       where attribute_n does not contain '*', the current ACL plugin
       accepts any attribute_n value even if it is not defined in the
       schema.  This patch rejects the aci if it contains attribute_n
       not defined in schema with this error message:
       NSACLPlugin - targetattr "attribute_n" does not exist in schema.
       Please add attributeTypes "attribute_n" to schema if necessary.
       The message is logged in the error log as well as returned to
       the client.
    2. To implement 1, slapi APIs slapi_attr_syntax_exists is added.
    3. An attributeTypes "connection" is added to 01core389.ldif which
       is referred in an aci of cn=monitor.