[Fleet] Handle unavailable spaces in agent policy space selector

[jillguyonnet]

Summary

Closes https://github.com/elastic/kibana/issues/193827

This PR improves the space selector in agent policy setting to handle the case where the user does not have access to all policy spaces.

In this case:

• Space selection is disabled
• The "Create space" link is hidden
• A tooltip is shown to inform the user why the input is disabled
• The inaccessible space badges are given an Unavailable space badge

Screenshots

For a user with access to all policy spaces (no change):

For a user with access to only a subset of policy spaces:

Checklist

• [x] Any text added follows EUI's writing guidelines, uses sentence case text and includes i18n support
• [x] Unit or functional tests were updated or added to match the most common scenarios
• [x] The PR description includes the appropriate Release Notes section, and the correct release_note:* label is applied per the guidelines

[elasticmachine]

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[nchaulet]

This looks a good solution to me, we should probably remove the space_ids property when that field is disabled from the data we send to update the policy here https://github.com/elastic/kibana/blob/main/x-pack/plugins/fleet/public/applications/fleet/sections/agent_policy/details_page/components/settings/index.tsx#L108

[elasticmachine]

:green_heart: Build Succeeded

• Buildkite Build
• Commit: 9564563eb2aa7409640d1d5a627fdaa4e481a00f

Metrics [docs]

Async chunks

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

id	before	after	diff
fleet	1.7MB	1.7MB	+546.0B

History

• :broken_heart: Build #253301 failed 576dc666edf3d0b6896c3d81db31e138c8477b63

cc @jillguyonnet