Deprecate `source-id` in favor of `source-ids`

[Fokko]

Feature Request / Improvement

Iceberg V3 introduces multi-column transforms that take more than one column as the input. For PyIceberg it would be good to deprecate source-id on both PartitionSpec and SourceOrder in favor of source-ids.

[Fokko]

Let's wait to see what comes out of apache/iceberg#12161

[Fokko]

Since we allow both source-id and source-ids for V3: apache/iceberg#12644. I don't think this issue is relevant anymore. I'll go ahead and close it for now.