Fix msearch rest-api-spec

[pquentin]

The code that reads these parameters is a bit scattered:

• include_named_queries_score
• index, ignore_unavailable, ignore_throttled, routing, allow_no_indices, expand_wildcards

I've tested that all those parameters are accepted.

[elasticsearchmachine]

Pinging @elastic/es-search-foundations (Team:Search Foundations)

[javanna]

Thanks for fixing this, how did this come up?

In general, when I see this type of changes, my first reaction is "oh, does this really work?". I think adding a small yaml test for each of the new parameters would help increase that confidence.

[pquentin]

Thanks for fixing this, how did this come up?

I'm working on fixing the inconsistencies between https://github.com/elastic/elasticsearch-specification and rest-api-spec (as tracked in elastic/elasticsearch-specification#4796) in order to ultimately generate the rest-api-spec from the Elasticsearch specification. The broader context is that we're working towards moving the Elasticsearch specification to Elasticsearch itself.

I understand why you would want a small YAML test, but it's not easy for me to do, especially as I'm currently dealing with 40 similar errors.