dictGet('name', ...) should check for XML dictionary 'name' if XML dict=name does not exists then use SQL dictionary from the currectDatabase()

*
 * <external_group>
 *     <external_config>
 *         <external_name>name</external_name>
 *         ....
 *     </external_config>
 * </external_group>
 */
struct ExternalLoaderConfigSettings
{
    std::string external_config;
    std::string external_name;
    std::string external_database;
    std::string external_uuid;
};
/** Interface for manage user-defined objects.
  * Monitors configuration file and automatically reloads objects in separate threads.
  * The monitoring thread wakes up every 'check_period_sec' seconds and checks
  * modification time of objects' configuration file. If said time is greater than
  * 'config_last_modified', the objects are created from scratch using configuration file,
  * possibly overriding currently existing objects with the same name (previous versions of
  * overridden objects will live as long as there are any users retaining them).
  *
  * Apart from checking configuration file for modifications, each object
  * has a lifetime of its own and may be updated if it supportUpdates.
  * The time of next update is calculated by choosing uniformly a random number
  * distributed between lifetime.min_sec and lifetime.max_sec.
  * If either of lifetime.min_sec and lifetime.max_sec is zero, such object is never updated.
  */
class ExternalLoader