Add a way for performing advanced queries in the XWiki integration

In the Eclipse Workbench we have the SPARQL visual editor which allows us to build very complex queries on the extracted knowledge.
In the XWiki integration, it would be nice to have something that allows to do something similar without being so advanced.

For example we might add a "query template (textual) editor" that will be used for creating different kind of predefined queries. When the user wants to perform an advanced search she can be choose one of these templates and fill the missing data as they see fit.