Flink : add watermark support for streaming read

[zhangjun0x01]

in order to support flink eventtime,I think we should add watermark support for flink streaming read.

[Reo-LEI]

Recently, I try use event time on flink streaming read. I remove the validation of watermark on FlinkCatalog, and I found the watermark can work correctly. I think the watermark is the ability of flink, not the iceberg. So I want to figure out what should we need to support to iceberg for use watermark on flink streaming read. @zhangjun0x01 @openinx @cwsteinbach

[github-actions]

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[github-actions]

This issue has been closed because it has not received any activity in the last 14 days since being marked as 'stale'