Directory REST endpoint should accept pagination and sorting arguments

We believe that the Directory REST endpoint could be improved in order to be paginated and sortable.
Also for the sake of coherency, since we have the following situation:

• The "/directory" endpoint is not paginated nor sortable;
• The "directoryObject" endpoint is paginated but does not accept any kind of ordering/comparator;

We can foresee some use cases that would need this improvement but, specifically on WebUI, it would avoid to sort the object client side.