add inner_hits field to KnnQuery within search (#2422)

(cherry picked from commit 6a1243d)

Author: Anaethelion

output/openapi/elasticsearch-serverless-openapi.json

@@ -219,6 +219,7 @@ json-processor,https://www.elastic.co/guide/en/elasticsearch/reference/{branch}/
 k-precision,https://www.elastic.co/guide/en/elasticsearch/reference/{branch}/search-rank-eval.html#k-precision
 k-recall,https://www.elastic.co/guide/en/elasticsearch/reference/{branch}/search-rank-eval.html#k-recall
 kv-processor,https://www.elastic.co/guide/en/elasticsearch/reference/{branch}/kv-processor.html
+knn-inner-hits,https://www.elastic.co/guide/en/elasticsearch/reference/{branch}/knn-search.html#nested-knn-search-inner-hits
 logstash-api-delete-pipeline,https://www.elastic.co/guide/en/elasticsearch/reference/{branch}/logstash-api-delete-pipeline.html
 logstash-api-get-pipeline,https://www.elastic.co/guide/en/elasticsearch/reference/{branch}/logstash-api-get-pipeline.html
 logstash-api-put-pipeline,https://www.elastic.co/guide/en/elasticsearch/reference/{branch}/logstash-api-put-pipeline.html

output/schema/schema.json

@@ -20,6 +20,7 @@
 import { Field } from '@_types/common'
 import { long, float } from '@_types/Numeric'
 import { QueryContainer } from './query_dsl/abstractions'
+import { InnerHits } from '@global/search/_types/hits'
 
 export type QueryVector = float[]
 
@@ -40,6 +41,11 @@ export interface KnnQuery {
   filter?: QueryContainer | QueryContainer[]
   /** The minimum similarity for a vector to be considered a match */
   similarity?: float
+  /**
+   * If defined, each search hit will contain inner hits.
+   * @doc_id knn-inner-hits
+   */
+  inner_hits?: InnerHits
 }
 
 /** @variants container */