🐛 fix: allow cluster-scoped resources to bypass allowedNamepsaces checks

[andclt]

What type of PR is this?

/kind bug

What this PR does / why we need it:

This PR fixes a bug where cluster-scoped resources cannot use AWS identities that have allowedNamespaces restrictions.

The permission check in isClusterPermittedToUsePrincipal() assumes all resources have a namespace, but cluster-scoped resources return an empty namespace (""), causing them to fail
allowedNamespaces validation even when they should be allowed.

This fix allows cluster-scoped resources to bypass allowedNamespaces checks since:

1. Cluster-scoped resources don't belong to a namespace
2. The allowedNamespaces field is designed for namespace-scoped resources to enforce multi-tenancy
3. Cluster-scoped resources are already protected by cluster-level RBAC (only cluster admins can create them)

Changes:

• Added isClusterScopedResource() helper that uses RESTMapper to query resource scope metadata from CRD definitions.
• Cluster-scoped resources bypass allowedNamespaces validation

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #6087
https://redhat.atlassian.net/browse/ROSAENG-60948

Special notes for your reviewer:

AI Usage:

None

Checklist:

• squashed commits
• includes documentation
• includes AI generated content
• includes emoji in title
• adds unit tests
• adds or updates e2e tests

Release note:

fix: allow cluster-scoped resources to bypass allowedNamepsaces checks

[kubernetes-prow]

Hi @andclt. Thanks for your PR.

I'm waiting for a kubernetes-sigs member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work.

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[damdo]

/assign @nrb

[serngawy]

/ok-to-test

[serngawy]

looks good to me

[nrb]

/lgtm
/approve

[kubernetes-prow]

LGTM label has been added.

Details

Git tree hash: f7f0e962693f6fe4cd52a61e15c27d4431778c7c

[kubernetes-prow]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: nrb

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Needs approval from an approver in each of these files:

• OWNERS [nrb]

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[damdo]

/hold

for testing

[damdo]

/test ?

[damdo]

/test pull-cluster-api-provider-aws-e2e