Adding retriever specification to _search API

[pmpailis]

This PR adds the retriever specification to the _search API, as is also defined in the 8.14.0 documentation to be released here .

Closes #2508

[pmpailis]

Running make validate locally I get many errors that seem to be unrelated to my changes:

✖ ../output/typescript/types.ts(2894,3): error TS2411: Property 'filters' of type 'Record<string, QueryDslQueryContainer>' is not assignable to 'string' index type 'never'.

export interface AggregationsAdjacencyMatrixAggregation extends AggregationsBucketAggregationBase {
  filters?: Record<string, QueryDslQueryContainer>
  separator?: string
}

[carlosdelest]

Running make validate locally I get many errors that seem to be unrelated to my changes:

I wouldn't worry about those, as you mention they are not related to your changes. Given that make compile works and make validate does not refer to errors added by your code, I think this is ready for review by the clients team when you feel ready 👍

[pmpailis]

Thanks @carlosdelest ! AFAICT there are no new validation errors introduced with these changes, as I'll mark it for review and we can take it from there. :)

[Anaethelion]

Overall looks good, I've left a few suggestions to make sure we get the field type right.

Can you check about the RRF Retriever field being optional ? I hav en't found anything that goes in that direction but I may have missed something.

[pmpailis]

Can you check about the RRF Retriever field being optional ?

Do you mean the rrf field in RetrieverContainer (link)? If so, it shouldn't be mandatory, we could still have a retriever-based request without rrf (e.g. using just kNN or the standard retriever).

[pmpailis]

Thanks for taking a look @Anaethelion ! I've pushed some changes as per your suggestions :)

[github-actions]

Following you can find the validation results for the APIs you have changed.

API	Status	Request	Response
knn_search	🔴	3/4	3/4
search	🔴	1421/2060	1992/2042

You can validate these APIs yourself by using the make validate target.

[Anaethelion]

LGTM!