Refactor thesaurus query build

- Look for text nodes and infer the concepts behind term using thesaurus
- Use value objects for thesaurus terms and concepts
- Pass a QueryContext holding allowed fields and locales informations when building the Elasticsearch query
- Change type hinting and name of query building method on nodes
- Remove unused method Node#isFullTextOnly()
- Move getFieldsStructure from RecordIndexer to RecordHelper for reusing field structure in SearchEngine

lib/Alchemy/Phrasea/SearchEngine/Elastic/Search/Query.php

@@ -23,19 +23,9 @@ class Query
         return $this->root->getTextNodes();
     }
 
-    /*
-     * This method seems weird to me, the implementation returns true when the
-     * query doesn't contain IN statements, but that doesn't define a full text
-     * search.
-     */
-    public function isFullTextOnly()
+    public function build(QueryContext $context)
     {
-        return $this->root->isFullTextOnly();
-    }
-
-    public function getElasticsearchQuery($fields = array())
-    {
-        return $this->root->getQuery($fields);
+        return $this->root->buildQuery($context);
     }
 
     public function dump()