Support prepare/close in UDF (#1985)

The prepare/close step of scalar function is already supported in execution framework, We only need to do is that support it in syntax and meta in frontend.

In addition, 'Hive' binary type of scalar function NOT supports prepare/close step, we need to make it supports.

be/src/udf_samples/udf_sample.cpp

@@ -26,4 +26,9 @@ IntVal AddUdf(FunctionContext* context, const IntVal& arg1, const IntVal& arg2)
     return {arg1.val + arg2.val};
 }
 
+/// --- Prepare / Close Functions ---
+/// ---------------------------------
+void AddUdfPrepare(FunctionContext* context, FunctionContext::FunctionStateScope scope) {}
+void AddUdfClose(FunctionContext* context, FunctionContext::FunctionStateScope scope) {}
+
 }