Add support for CDC partitioner/per-table partitioners

[piodul]

Recently, Scylla gained support for tables with custom partitioners. In this context, a partitioner is an algorithm which computes a token (a i64 value) from a partition key. When a table uses a custom partitioner, its data is distributed differently - based on the custom partitioner, not the global partitioner.

Shard/token aware drivers which are unaware of this - just like this one - will calculate wrong tokens and will choose wrong replicas and shards when doing operations on those tables. Shard/token awareness won't work correctly for those tables.

Currently, only CDC log tables have a custom partitioner.

We should implement support for custom partitioners and the CDC partitioner.

References:

• Info about how token is encoded in the cdc$stream_id column: https://github.com/scylladb/scylla/blob/master/docs/design-notes/cdc.md#stream-ids
• PR that implements support for this in gocql: Add support for the CDC partitioner gocql#69
• PRs that implement support for this in java-driver: Add CDC partitioner (version 3.10.2) java-driver#35 Add CDC partitioner (Version 4.9.0) java-driver#37