OPENDJ-1122 (CR-7120) Fix control panel in remote mode

This commit makes the control panel work in remote mode by solving missing schema elements issues.

* src/main/java/org/opends/guitools/controlpanel/datamodel/ControlPanelInfo.java
** Initialialize configuration framework to ensure remote server configuration can be successfully read (cause of the NPE mentioned in the issue)

* src/main/java/org/opends/guitools/controlpanel/util/RemoteSchemaLoader.java
** Add missing matching rules and attribute syntaxes to the local schema before read remote server schema.

* src/main/java/org/opends/guitools/controlpanel/util/SchemaLoader.java
** Consequences of changes in RemoteSchemaLoader