Fix/IAM role policy output

[Arzianghanchi]

what

• Uses aws_iam_role_policy.default[*].policy to safely handle conditional resources.
• Returns an empty list instead of failing when no policy exists.
• updated examples to demonstrate how to use AWS-managed policies effectively.

why

• Splat expressions ([*]) gracefully handle empty resource collections created via count or for_each
• Avoids index-based failures by treating the resource as a list (empty or populated)

references

• Terraform docs: Splat Expressions