feat: add data source codec extension seam

[wirybeaver]

Which issue does this PR close?

Part of #1241.

What changes are included?

Adds a small, format-neutral serialization seam for external data-source integrations:

• BallistaTableProviderCodec for logical table-provider transport
• BallistaPhysicalPlanCodec for format-specific execution plans
• a named envelope so decoding dispatches by stable codec name rather than registration order
• explicit claim/decline encoding through Option<Vec<u8>>

Ballista's own logical and physical nodes keep their existing path and priority. Core gains no Hudi, Iceberg, Delta, or Lance dependency, and behavior is unchanged when no codec is registered.

A follow-up Hudi integration uses this seam for a distributed copy-on-write read.

Tests

• cargo test -p ballista-core --lib serde::test
• cargo clippy -p ballista-core --lib --tests -- -D warnings

The focused tests cover logical provider transport, physical plan transport, stable name dispatch, and the existing Ballista-plan regression.

[milenkovicm]

I'm not sure that i understand why is this needed in ballista main ?
ballista codec is fully pluggable at the moment, implementers can plug in its own implementation hence i dont see this needed in main, please correct me if i'm wrong