Fix irreproducible inference due to the imprecise floating point values in xgboost's get_dump (#500)

Add new parser `model/xgboost+json+raw` to support xgboost's JSON output when using `get_dump` 

fixes #497

Author: pltb

src/main/java/com/o19s/es/ltr/LtrQueryParserPlugin.java

@@ -47,6 +47,7 @@
 import com.o19s.es.ltr.ranker.parser.LinearRankerParser;
 import com.o19s.es.ltr.ranker.parser.LtrRankerParserFactory;
 import com.o19s.es.ltr.ranker.parser.XGBoostJsonParser;
+import com.o19s.es.ltr.ranker.parser.XGBoostRawJsonParser;
 import com.o19s.es.ltr.ranker.ranklib.RankLibScriptEngine;
 import com.o19s.es.ltr.ranker.ranklib.RanklibModelParser;
 import com.o19s.es.ltr.rest.RestCreateModelFromSet;
@@ -129,6 +130,7 @@ public LtrQueryParserPlugin(Settings settings) {
                 .register(RanklibModelParser.TYPE, () -> new RanklibModelParser(ranklib.get()))
                 .register(LinearRankerParser.TYPE, LinearRankerParser::new)
                 .register(XGBoostJsonParser.TYPE, XGBoostJsonParser::new)
+                .register(XGBoostRawJsonParser.TYPE, XGBoostRawJsonParser::new)
                 .build();
     }