WIP: feat: eks pod identity support for controllers

[richardcase]

What type of PR is this?

/kind feature

What this PR does / why we need it:

This adds support for using EKS pod identity for the CAPA controller when the management cluster is an EKS cluster.

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 #

Special notes for your reviewer:

This is in addition to #4906 .

Checklist:

• squashed commits
• includes documentation
• includes emojis
• adds unit tests
• adds or updates e2e tests

Release note:

Add support for using EKS pod identity for the controller credentials.

[k8s-ci-robot]

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[k8s-ci-robot]

@richardcase: The following test failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
pull-cluster-api-provider-aws-test	352d969	link	true	/test pull-cluster-api-provider-aws-test

Full PR test history. Your PR dashboard. Please help us cut down on flakes by linking to an open issue when you hit one in your PR.

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