[serverless] Create Search Serverless plugin

[clintandrewhall]

Derived from #153274
Builds upon #155582

Summary

This PR creates the Serverless Search plugin, based on the work from #153274:

• creates the plugin,
• adds API to hide the solution navigation from Enterprise Search,
• calls that API if the chrome style is project.
• nit: fixes warnings from eslint in the files this PR touched.

Next Steps

• render the left nav from [serverless][poc] Unified Navigation #153274 using an API provided by @elastic/appex-sharedux
  • this low-level API should be coming in the next few days.

[jbudz]

limits.yml

[sphilipse]

This LGTM overall, one question on CODEOWNERS

[kibana-ci]

💚 Build Succeeded

• Buildkite Build
• Commit: 7704ca6

Metrics [docs]

Module Count

Fewer modules leads to a faster build time

id	before	after	diff
serverlessSearch	-	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
enterpriseSearch	7	9	+2
serverlessSearch	-	6	+6
total			+8

Async chunks

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

id	before	after	diff
enterpriseSearch	2.3MB	2.3MB	+111.0B

Page load bundle

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

id	before	after	diff
enterpriseSearch	31.5KB	31.7KB	+194.0B
serverlessSearch	-	1.5KB	+1.5KB
total			+1.7KB

Unknown metric groups

API count

id	before	after	diff
enterpriseSearch	7	9	+2
serverlessSearch	-	6	+6
total			+8

ESLint disabled line counts

id	before	after	diff
enterpriseSearch	17	19	+2
securitySolution	399	402	+3
serverlessSearch	-	4	+4
total			+9

Total ESLint disabled count

id	before	after	diff
enterpriseSearch	18	20	+2
securitySolution	479	482	+3
serverlessSearch	-	4	+4
total			+9

History

• 💔 Build #124118 failed 66a274c
• 💔 Build #123992 failed 621ba14

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@elasticmachine merge upstream