[Search] search_indices: scaffold empty plugin

[TattdCodeMonkey]

Summary

Scaffolding empty plugin for development of day 0 onboarding work. This plugin is currently disabled by default and will be enabled for ES3 when it's ready for users.

[TattdCodeMonkey]

@elasticmachine merge upstream

[kibana-ci]

💛 Build succeeded, but was flaky

• Buildkite Build
• Commit: c91a2c7

Failed CI Steps

Metrics [docs]

Module Count

Fewer modules leads to a faster build time

id	before	after	diff
searchIndices	-	4	+4

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
searchIndices	-	6	+6

Page load bundle

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

id	before	after	diff
searchIndices	-	1.5KB	+1.5KB

Unknown metric groups

API count

id	before	after	diff
searchIndices	-	6	+6

ESLint disabled line counts

id	before	after	diff
searchIndices	-	4	+4

Total ESLint disabled count

id	before	after	diff
searchIndices	-	4	+4

History

• 💚 Build #228648 succeeded d823150
• 💔 Build #228610 failed 9825b80c8f01a547fbc1f9e5c3fedcb8a1bf2ab5
• 💔 Build #228421 failed 0b24897295d8cebf5a29105d96dff53c0896d192

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

[afharo]

LGTM.

A general thought: declaring dependencies before being actively used might end up with those dependencies never being removed.

IIRC, the long-term plan is to add a CI step that checks that dependencies are used. Although it's not completed yet 😇

[afharo]

nit: since the plugin doesn't export any contract yet, I'd hold off declaring the dependency unless there's any specific reason to force a certain order in the execution of the plugins.