Allow wildcard matching of service account subject

[avoidik]

Description

This PR adds --subject-pattern to eksctl create iamserviceaccount.

#8628

Checklist

• Added tests that cover your change (if possible)
• Added/modified documentation as required (such as the README.md, or the userdocs directory)
• Manually tested
• Made sure the title of the PR is a good description that can go into the release notes
• (Core team) Added labels for change area (e.g. area/nodegroup) and kind (e.g. kind/improvement)

BONUS POINTS checklist: complete for good vibes and maybe prizes?! 🤯

• Backfilled missing tests for code in same general area 🎉
• Refactored something and made the world a better place 🌟

[avoidik]

Example:

eksctl create iamserviceaccount \
    --name crossplane \
    --namespace crossplane-system \
    --cluster "$CLUSTER_NAME" \
    --role-name "$ROLE_NAME" \
    --attach-policy-arn 'arn:aws:iam::aws:policy/AdministratorAccess' \
    --subject-pattern 'provider-aws-*' \
    --role-only \
    --approve

[NicholasBlaskey]

Feature looks reasonable to me. Thanks for contributing a fix

Implementation looks good to me just have a comment couples

[avoidik]

@NicholasBlaskey I've regenerated the schema, I believe my PR is now ready, please have a look