Optional Iceberg commit locks

[sauliusvl]

When multiple threads attempt committing Iceberg transactions to the same table at the same time they can end up conflicting with each other resulting it multiple retries. Even though commits eventually succeed, this can effectively prolong commit times and result in lots of warning messages in logs. Hence we add an option to specify a lock to use when performing commits.

Also:

• fix flaky Iceberg test that randomly failed to download the extension, download it locally once on startup instead
• add a builder for IcebergRecordBatchStorage
• bump all libraries
• override zstd dependency scheme so that we can bump the patch version