[DBZ-PGYB] Add transformer PGCompatible to emit events with standard structure

[vaibhav-yb]

This PR adds a transformer PGCompatible with full path io.debezium.connector.postgresql.transforms.yugabytedb, this will be helpful in converting the structure of the emitted events to match the one emitted by standard Debezium connectors.

Example:
Consider the following schema for a table test: (id INT PRIMARY KEY, name TEXT, age INT)

• If a record is inserted having values (1, 'John Doe', 25) then after using the above transformer, the payload of the record would look like:

"payload": {
  "id": 1,
  "name": "John Doe",
  "age": 25
}

• If the same record is now updated and age is changed to 30 i.e. UPDATE test SET age = 30 WHERE id = 1; then the payload would look like:

"payload": {
  "id": 1,
  "name": null,
  "age": 30
}

NOTE: The above example assumes that the replica identity of the table is CHANGE and that is how the assumption was made that the UPDATE event will not contain the value for the fields which were not updated. For more information on replica identity, see YugabyteDB docs.