Flink: Backport support source watermark for flink sql windows

[swapna267]

Backport changes in #12191 to 1.18,1.19

Iceberg Source to support Source Watermark, so it can be used in Flink WINDOW functions. https://github.com/apache/flink/blob/release-1.18/flink-table/flink-table-common/src/main/java/org/apache/flink/table/connector/source/abilities/SupportsSourceWatermark.java enables Flink to rely on the watermark strategy provided by the ScanTableSource itself.

CREATE TABLE table_wm (
      eventTS AS CAST(t1 AS TIMESTAMP(3)),
      WATERMARK FOR eventTS AS SOURCE_WATERMARK()
) WITH (
  'watermark-column'='t1'
) LIKE iceberg_catalog.db.table;

Reference:
#10219
#9346

[swapna267]

@pvary this is a clean backport. There were some checks not related to my code were failing in first commit, so had to make dummy commit to re-trigger tests.

[pvary]

Merged to main.
Thanks for the PR @swapna267!