[FLINK-36611][pipeline-connector][kafka] Add schema info to output of Kafka sink

[MOBIN-F]

Currently, the output of Kafka sink in debezium format looks like this:

{
  "before": {
    "id": 4,
    "name": "John",
    "address": "New York",
    "phone_number": "2222",
    "age": 12
  },
  "after": {
    "id": 4,
    "name": "John",
    "address": "New York",
    "phone_number": "1234",
    "age": 12
  },
  "op": "u",
  "source": {
    "db": null,
    "table": "customers"
  }
} 

It contains record data with full before/after and db info, but schema info wasn't included.

However, In some scenarios, we need this information to determine the type of data. For example, Paimon's Kafka CDC source requires this type information, otherwise all types are considered String, refer to https://paimon.apache.org/docs/0.9/flink/cdc-ingestion/kafka-cdc/#supported-formats.

Considering that this will increase the data load, I suggest adding a parameter to configure whether to enable it.

[MOBIN-F]

Through the jsonConverter.asJsonSchema(valueSchema) method, we can easily obtain the complete schema json information of debezium-json.
At first, I wanted to convert the schema josn to GenericRowData, but the schema structure of debezium is too complex and difficult to implement.
Finally, I chose to pass the schema json information as a string to the downstream, which can reduce some serialization and deserialization overhead

[MOBIN-F]

Because the schema is passed to the downstream as a string, and there is a nested json in the schema, if the json string is put into jsonNode, there will be ["]. The JsonNode.asText() method can solve this problem well.