fix: Fix efs csi driver mount issues

[askulkarni2]

What does this PR do?

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1. Updates IAM policy for EFS driver IRSA for missing permissions required for IAM Access Control
2. Updates stateful example with mount_options=["iam"] to use IAM access control to fix the Access Denied errors. This will fix errors in CloudTrail that an anonymous principal tries to mount your EFS.
3. Refactors add-on module to use new conventions

Motivation

• Resolves Mount issues with module aws_efs_csi_driver #1171

More

• Yes, I have tested the PR using my local account setup (Provide any test evidence report under Additional Notes)
• [N/A] Yes, I have added a new example under examples to support my PR
• [N/A] Yes, I have created another PR for add-ons under add-ons repo (if applicable)
• [N/A] Yes, I have updated the docs for this feature
• Yes, I ran pre-commit run -a with this PR

Note: Not all the PRs require a new example and/or doc page. In general:

• Use an existing example when possible to demonstrate a new addons usage
• A new docs page under docs/add-ons/* is required for new a new addon

For Moderators

• E2E Test successfully complete before merge?

Additional Notes