[SEDONA-555] Snowflake Native App should not always create a new role (#1401)

Author: jiayuasu

snowflake/src/main/java/org/apache/sedona/snowflake/snowsql/ddl/DDLGenerator.java

@@ -81,7 +81,7 @@ public static void main(String[] args) {
             }
             stageName = "";
             System.out.println("-- Generating DDL for Snowflake Native App");
-            System.out.println("CREATE APPLICATION ROLE " + appRoleName + ";");
+            System.out.println("CREATE APPLICATION ROLE IF NOT EXISTS " + appRoleName + ";");
             System.out.println("CREATE OR ALTER VERSIONED SCHEMA sedona;");
             System.out.println("GRANT USAGE ON SCHEMA sedona TO APPLICATION ROLE " + appRoleName + ";");
         }