Unify clustered queries with non clustered queries

Clustered queries currently have a different method, and they work on top on non-shared indexes.
We should detect (or make it explicitly configurable) the fact that the index is not shared and use clustered query internally, but exposing a single method, with a new parameter to allow doing a query in a single step or two steps (broadcast).

Last, but not least, we should offer the possibility to broadcast Ickle queries apart from Lucene Queries, as Ickle queries are String and don't have serialization issues.