Add annoy index type in C++ sdk (#1826)

Signed-off-by: fishpenguin <kun.yu@zilliz.com>

CHANGELOG.md

@@ -9,6 +9,7 @@ Please mark all change in change log and use the issue from GitHub
 
 ## Feature
 -   \#1655 GPU index support delete vectors
+-   \#1825 Add annoy index type in C++ sdk
 
 ## Improvement
 

sdk/examples/utils/Utils.cpp

@@ -94,6 +94,8 @@ Utils::IndexTypeName(const milvus::IndexType& index_type) {
         case milvus::IndexType::IVFPQ:return "IVFPQ";
         case milvus::IndexType::SPTAGKDT:return "SPTAGKDT";
         case milvus::IndexType::SPTAGBKT:return "SPTAGBKT";
+        case milvus::IndexType::HNSW:return "HNSW";
+        case milvus::IndexType::ANNOY:return "ANNOY";
         default:return "Unknown index type";
     }
 }

sdk/include/MilvusApi.h

@@ -35,6 +35,7 @@ enum class IndexType {
     SPTAGKDT = 7,
     SPTAGBKT = 8,
     HNSW = 11,
+    ANNOY = 12,
 };
 
 enum class MetricType {