Add support for Iceberg

[andygrove]

What is the problem the feature request solves?

This issue is to track the status of Iceberg support in Comet.

There is a PR open against Iceberg to make use of Comet's native Parquet decoding:

apache/iceberg#9841

Once this is merged and a new Iceberg release is available, Comet will be updated to support reading from Iceberg.

Describe the potential solution

No response

Additional context

It maybe possible to read from Iceberg today by enabling spark.comet.sparkToColumnar.enabled and adding the Iceberg scan operator to spark.comet.sparkToColumnar.supportedOperatorList but this has not been tested, and may not perform well.

[viirya]

Related issue: #974