public void open(FunctionContext context) throws IOException {
    init(context);
    start();
  }
Open the lookup function, e.g.: create {@link KVTable} kvTable, and load data.

@throws IOException If serialize or deserialize failed
amoro-format-mixed/amoro-mixed-flink/amoro-mixed-flink-common/src/main/java/org/apache/amoro/flink/lookup/BasicLookupFunction.java