[Infra Monitoring UI] add tech preview for hosts view

[neptunian]

Closes #139589

Adds option in Stack Management > Advanced Settings to preview the Infrastructure Hosts View:

If enabled, should appear in the navigation under Infrastructure:

If enabled, should appear in search results:

[elasticmachine]

Pinging @elastic/infra-monitoring-ui (Team:Infra Monitoring UI)

[miltonhultgren]

LGTM 👍🏼

I only got "stuck" on the fact that I had to reload the page for the side nav to update, I wonder if we can somehow make it update in response to the setting changing?

I think it should be possible to get an observable from uiSettings?

[smith]

I think it should be possible to get an observable from uiSettings?

@miltonhultgren I think you're right. Looks like a few other plugins do it like this:

import useObservable from 'react-use/lib/useObservable';
const isHostsViewEnabled = useObservable<boolean>(core.uiSettings.get$(enableInfrastructureHostsView));

Haven't tried this to see if it will work without having to reload the page but it might work.

[kibana-ci]

💚 Build Succeeded

• Buildkite Build
• Commit: eca9627

Metrics [docs]

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
observability	497	505	+8

Page load bundle

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

id	before	after	diff
infra	84.5KB	84.6KB	+150.0B
observability	64.9KB	65.1KB	+210.0B
total			+360.0B

Unknown metric groups

API count

id	before	after	diff
observability	501	509	+8

History

• 💚 Build #72419 succeeded 30aa769
• 💔 Build #72413 failed 8d49631

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