[KQL] Add util for getting field names from KQL expression

[lukasolson]

Summary

Resolves #180555.

Adds a utility to kbn-es-query for getting the field names associated with a KQL expression.

This utility already (mostly) existed in x-pack/plugins/observability_solution/apm/common/utils/get_kuery_fields.ts but didn't have test coverage for things like wildcards and nested fields. This also updates the utility to be a little more robust in checking the KQL node types.

Checklist

• Documentation was added for features that require explanation or tutorials
• Unit or functional tests were updated or added to match the most common scenarios

[lukasolson]

/ci

[mattkime]

/ci

[elasticmachine]

Pinging @elastic/kibana-data-discovery (Team:DataDiscovery)

[elasticmachine]

Pinging @elastic/obs-ux-management-team (Team:obs-ux-management)

[elasticmachine]

Pinging @elastic/obs-ux-infra_services-team (Team:obs-ux-infra_services)

[mattkime]

/ci

[dominiqueclarke]

obs-ux-management changes LGTM

[mattkime]

Changes look great and work well, thanks!

[kertal]

@elasticmachine merge upstream

[kibana-ci]

💚 Build Succeeded

• Buildkite Build
• Commit: e436b92
• Kibana Serverless Image: docker.elastic.co/kibana-ci/kibana-serverless:pr-183573-e436b929c052
• Observability Deployment

Metrics [docs]

Module Count

Fewer modules leads to a faster build time

id	before	after	diff
apm	1806	1805	-1

Public APIs missing comments

Total count of every public API that lacks a comment. Target amount is 0. Run node scripts/build_api_docs --plugin [yourplugin] --stats comments for more detailed information.

id	before	after	diff
@kbn/es-query	201	205	+4

Async chunks

Total size of all lazy-loaded chunks that will be downloaded as the user navigates the app

id	before	after	diff
apm	3.3MB	3.3MB	-139.0B

Canvas Sharable Runtime

The Canvas "shareable runtime" is an bundle produced to enable running Canvas workpads outside of Kibana. This bundle is included in third-party webpages that embed canvas and therefor should be as slim as possible.

id	before	after	diff
module count	-	5411	+5411
total size	-	8.8MB	+8.8MB

Page load bundle

Size of the bundles that are downloaded on every page load. Target size is below 100kb

id	before	after	diff
kbnUiSharedDeps-srcJs	3.1MB	3.1MB	+731.0B

Unknown metric groups

API count

id	before	after	diff
@kbn/es-query	261	265	+4

History

• 💚 Build #211063 succeeded e4797cc
• 💔 Build #210929 failed bb876f9
• 💔 Build #210615 failed e278819
• 💔 Build #210345 failed 6252119

To update your PR or re-run it, just comment with:
@elasticmachine merge upstream

cc @lukasolson

[kpatticha]

LGTM