✨ Add missing, desired routes during route table reconciliation

[AndiDog]

What type of PR is this?

/kind feature

What this PR does / why we need it:

For bring-your-own VPCs that miss routes such as 0.0.0.0/0, CAPA should create the desired routes. Therefore I implemented creation, while previously the code only fixed mismatching, existing routes (update). I specifically did not implement full reconciliation, i.e. deletion, since that could be a breaking, dangerous change.

This also includes an improvement for event/log formatting since %s can't format a struct reasonably.

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):

Special notes for your reviewer:

AI Usage:

I used Claude to create a failing test, then to rewrite and simplify existing logic to do both create+update. Basically the same as I would've done on my own, plus human check all along the way.

Checklist:

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

Release note:

Add missing, desired routes during route table reconciliation

[k8s-ci-robot]

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[kubernetes-prow]

[APPROVALNOTIFIER] This PR is NOT APPROVED

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• OWNERS

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[AndiDog]

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

[AndiDog]

/retest

I'm looking at that flake/race separately