[Iceberg] Handle missing snapshots in change timeline

[ashvina]

This issue is related to Iceberg's snapshot expiry. Iceberg API allows expiry of any snapshot, even if it is not the oldest snapshot or even if the snapshot is part of a multi-snapshot transaction. A scan cannot be initiated for an expired snapshot. OneTable replays changes on a target format. If a snapshot which is part of the timeline is expired, the replay cannot be performed. This case should be handled properly in OneTable. For e.g. this could result in termination of incremental sync?

Originally posted by @the-other-tim-brown in https://github.com/onetable-io/onetable/pull/129#discussion_r1375325454