Tasks and Segments should not have generic types

[andrus]

Tasks are used as generics-free LmTask instances, task builders do not have any API that can be assisted by generics.

Segments are used to process individual batches for a task internally store DataFrames, so they do not have a notion of generics type. There's nothing in the segment (other than declaration) that would define such a type.

So let's remove the generics parameter from tasks, task builders and segments.

Upgrade Notes

This affects listeners that accept segments as method parameters. There will be compilation errors, and the listeners must update their signatures, removing <T>.