[Fleet] Extract hook for agentList table logic

[criamico]

Closes #131153
Follow up of #175318

Summary

Extract the main logic for agentList component in a separate hook.

Checklist

• Unit or functional tests were updated or added to match the most common scenarios
• Flaky Test Runner was used on any tests changed

[apmmachine]

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[criamico]

/ci

[elasticmachine]

Pinging @elastic/fleet (Team:Fleet)

[criamico]

@elasticmachine merge upstream

[kibana-ci]

💚 Build Succeeded

• Buildkite Build
• Commit: 172785b

Metrics [docs]

Module Count

Fewer modules leads to a faster build time

id	before	after	diff
fleet	964	965	+1

Async chunks

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

id	before	after	diff
fleet	1.2MB	1.2MB	+1.3KB

History

• 💚 Build #189626 succeeded 8a14662

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

cc @criamico

[kpollich]

Overall LGTM! Love seeing hooks tested in isolation, as we didn't have much (if any) unit test style coverage of this logic before.

I think maybe a future pass at this would be to break the one gigantic hook down into smaller ones. Having a "god hook" like this has its tradeoffs (see the gigantic number of values returned by the hook), but this is an excellent improvement that helps us add test coverage to a key UI component in Fleet 🚀

[criamico]

I think maybe a future pass at this would be to break the one gigantic hook down into smaller ones.

That would be great, but I didn't want to go too deep in the rabbit hole. We can then iterate on this one and maybe try to simplify some of the calls we do on that page.