Deserialization failure handling

[ferenc-csaky]

This is a work in progress thing, just wanted to share ASAP for everyone to get the idea.

Relevant changes

• Modified classes excluded from the connector JAR.
• Copied the classes that has to be modified.
  • KafkaDynamicTableFactory defines the new table options (scan.deser.failure-handler, scan.deser.failure-topic) and passes their value.
  • KafkaDynamicSource in this context is just a connecting layer that passes through the newly added information.
  • DynamicKafkaDeserializationSchema is modified, a newly added deserWithFailureHandling method now can handle the exceptions accordingly.
• Added a skeleton logic for failure handling.

TODO

• The deserFailureTarget is now an empty shell, which should be a KafkaProducer, that has to be initialized accordingly.
• The same has to be done for the upsert-kafka classes too.
• Do some tests.

[ferenc-csaky]

@velo Would it be possible to skip the enforced code format for the classes that was duplicated from the flink-connector-kafka repo? I believe that code should be kept as is cause if it has to be updated from a more recent connector version, it would be much easier to track what actually changed if the format is kept as is.

[ferenc-csaky]

Superseded by #68