Handle Serde for Custom AggregateUDFImpl traits

[joroKr21]

Is your feature request related to a problem or challenge?

Currently, PhysicalExtensionCodec and LogicalExtensionCodec provide hooks for decoding and encoding custom scalar UDFs. But we're missing the same for aggregation UDFs.

Describe the solution you'd like

Add try_encode_udaf and try_decode_udaf functions to PhysicalExtensionCodec and LogicalExtensionCodec with default noop implementations. Add the required function definition fields (optional bytes) to the Proto messages.

Describe alternatives you've considered

There is no alternative currently. It's not possible to run a parameterized aggregation UDF in a distributed architecture.

Additional context

See #8706