Add include_execution_metadata to ES|QL query spec

[luigidellaquila]

With elastic/elasticsearch#134446 we are adding a new query parameter to ES|QL request: include_cps_metadata include_execution_metadata

The behavior is the same as include_ccs_metadata, but it will be available both on Serverless and Stateful, in the scope of Cross-Project Search and Cross-Cluster Search. Details here

[quux00]

Example of how I recently added some specs that are CPS specific:

https://github.com/elastic/elasticsearch-specification/pull/5259/files#diff-4114e335296798822015a064d77c5c6d14c797a89c76a0d08b63dcf5d4028651R231

I think the include_cps_response support is also behind this feature flag, so you'll probably want to do the same.