As a HyperShift developer
I want IAM migrated to AWS SDK v2
So that the IAM migration is complete

Acceptance Criteria:

• [ ] Migrate IAM role and OIDC provider management
• [ ] Update all unit tests with v2 mocks
• [ ] Update E2E test utilities
• [ ] make verify passes
• [ ] All tests pass

Files (IAM migration):

• /cmd/infra/aws/create_iam.go
• /cmd/infra/aws/iam.go
• /test/e2e/util/sharedoidc.go