CXX-1116 Provide definition of result::insert_many::result()

This method was declared as part of the API for this class, but no
definition was ever provided.

Author: jrassi

src/mongocxx/result/insert_many.cpp

@@ -24,14 +24,18 @@ insert_many::insert_many(result::bulk_write result, insert_many::id_map inserted
     : _result(std::move(result)), _generated_ids(std::move(inserted_ids)) {
 }
 
-insert_many::id_map insert_many::inserted_ids() {
-    return _generated_ids;
+const result::bulk_write& insert_many::result() const {
+    return _result;
 }
 
 std::int32_t insert_many::inserted_count() const {
     return _result.inserted_count();
 }
 
+insert_many::id_map insert_many::inserted_ids() {
+    return _generated_ids;
+}
+
 }  // namespace result
 MONGOCXX_INLINE_NAMESPACE_END
 }  // namespace mongocxx