OPENDJ-1929 Use SearchScope API in control panel

CR-6632
To avoid LocalDBVLVIndexDefn.Scope dependency in UI, we need to use a general API for VLV index scopes.
* org.opends.guitools.controlpanel.datamodel.VLVIndexDescriptor.java
** Replace LocalDBLocalDBVLVIndexCfgDefn.Scope by SearchScope as the scope class

* org.opends.guitools.controlpanel.datamodel.VLVIndexTableModel.java
** Use IllegalArgumentException instead of RuntimeException to be more consistent.

* org.opends.guitools.controlpanel.ui.VLVIndexPanel.java
** Use this change to take the opportunity to change the selectScopeRadioButton parameter type (use straight SearchScope instead of VLVIndexDescriptor)

* org.opends.guitools.controlpanel.ui.AbstractVLVIndexPanel.java
** Use SearchScope in getScope() method
** Use straight return
** throw a IllegalStateException instead of fall back on WHOLE_SUBTREE.

* Others modified files are consequences of modifications described above.