Move Writer classes from kafka-connect to core

[ismailsimsek]

Feature Request / Improvement

Move following classes to iceberg-core for downstream projects (debezium-server-iceberg,iceberg-kafka-connect) to reuse it.

Classes are located here: https://github.com/tabular-io/iceberg-kafka-connect/tree/main/kafka-connect/src/main/java/io/tabular/iceberg/connect/data

• BaseDeltaTaskWriter
• PartitionedAppendWriter
• PartitionedDeltaWriter
• UnpartitionedDeltaWriter
• RecordProjection

cc @bryanck what do you think about this? would it worth the change to do it?

Query engine

Kafka Connect

Willingness to contribute

• I can contribute this improvement/feature independently
• I would be willing to contribute this improvement/feature with guidance from the Iceberg community
• I cannot contribute this improvement/feature at this time

[github-actions]

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