JDBCPollInputOperator support for offset rebase

Operator currently cannot handle tables where old data is periodically removed, because the poll logic assumes a fixed start offset. Instead, it should support offset rebase with a trailing lower bound key.

Such use of the WHERE clause will also avoid repeated full index scanning and be especially efficient when the source is partitioned on the key column.

https://lists.apache.org/thread.html/50ae7799199ab8b9e38b7947dbcfd466b60df0bbfea6aa19abfd0b33@%3Cusers.apex.apache.org%3E