Add support for `allow_partial_search_results` search request parameter

[russcam]

Relates: elastic/elasticsearch#27906
Documentation: https://www.elastic.co/guide/en/elasticsearch/reference/current/search-uri-request.html#_parameters_3

Add support for allow_partial_search_results request parameter to return an overall failure if the request would produce partial results

[Mpdreamz]

This is part of the 6.3 branch after code generation.

[russcam]

Closing this as it's part in 6.3 codegen