Dataset pipeline follow ups (#2055)

Co-authored-by: Luca Forstner <luca.forstner@gmail.com>

Author: ankrgyl

.changeset/good-loops-end.md

@@ -0,0 +1,5 @@
+---
+"braintrust": minor
+---
+
+feat: Include span id in dataset pipeline argument

js/src/dataset-pipeline.ts

@@ -43,6 +43,7 @@ type DatasetPipelineDefinition<Scope extends "span" | "trace"> = {
   transform: (
     transformInput: Scope extends "span"
       ? {
+          id: string;
           input: unknown;
           output: unknown;
           expected: unknown;
@@ -83,6 +84,7 @@ type DatasetPipelineBtDefinition = {
   transform: (
     transformInput:
       | {
+          id: string;
           input: unknown;
           output: unknown;
           expected: unknown;