Return recall rate in search result for V2 (#1235)

Signed-off-by: yhmo <yihua.mo@zilliz.com>

sdk-core/src/main/java/io/milvus/v2/service/vector/VectorService.java

@@ -181,6 +181,7 @@ public class VectorService extends BaseService {
         return SearchResp.builder()
                 .searchResults(convertUtils.getEntities(response))
                 .sessionTs(response.getSessionTs())
+                .recalls(response.getResults().getRecallsList())
                 .build();
     }
 
@@ -197,6 +198,7 @@ public class VectorService extends BaseService {
 
         return SearchResp.builder()
                 .searchResults(convertUtils.getEntities(response))
+                .recalls(response.getResults().getRecallsList())
                 .build();
     }
 

sdk-core/src/main/java/io/milvus/v2/service/vector/response/SearchResp.java

@@ -30,6 +30,7 @@ import java.util.Map;
 public class SearchResp {
     private List<List<SearchResult>> searchResults;
     private long sessionTs = 1L; // default eventually ts
+    private List<Float> recalls;
 
     @Data
     @SuperBuilder