Instrument data plugin with ExecutionContextService

[mshustov]

Summary

An example of ExecutionContextService (added in elastic#102039) integration with data plugin. Any suggestions about API improvements are welcome.

The data plugin data fetching model is a bit different from the one most plugins use. It doesn't send an HTTP request for every search operation, but batches them according to some internal rules and send them in bulk. In turn, the Kibana server parses the batch and issues a dedicated search request for every search operation. Kibana server streams Elasticsearch server response back to the browser as soon as every search operation is finished.

Checklist

Delete any items that are not applicable to this PR.

• Any text added follows EUI's writing guidelines, uses sentence case text and includes i18n support
• Documentation was added for features that require explanation or tutorials
• Unit or functional tests were updated or added to match the most common scenarios
• Any UI touched in this PR is usable by keyboard only (learn more about keyboard accessibility)
• Any UI touched in this PR does not create any new axe failures (run axe in browser: FF, Chrome)
• If a plugin configuration key changed, check if it needs to be allowlisted in the cloud and added to the docker list
• This renders correctly on smaller devices using a responsive layout. (You can test this in your browser)
• This was checked for cross-browser compatibility

For maintainers

• This was checked for breaking API changes and was labeled appropriately