Refactor Elasticsearch Page Provider

There are 2 page providers in nuxeo-elasticsearch:

• The native page provider which was written first and that impl all the predicate logic and parameter escaping.

• The NXQL page provider which just extend native page provider and uses a NXQL to ES converter for the fixed part.

Because we now have an NXQL to ES converter, it will be easier to extend CoreQueryDocumentPageProvider to get the NXQL and use the converter.

This will remove code duplication.

Also instead of having 2 page providers we can add an ad hoc predicate to submit native ES query syntax.