Assume Role List Parsing

assume_role: preserve commas inside list expressions

Terragrunt previously failed to correctly parse assume_role attributes containing list values such as transitive_tag_keys or policy_arns. Commas inside nested list expressions were incorrectly treated as top-level separators, causing generated configurations to fail with parsing errors.

assume_role = {
  role_arn            = "arn:aws:iam::123456789012:role/test-role"
  transitive_tag_keys = ["Project", "Projects"]
}

This resulted in errors similar to:

Missing item separator; Expected a comma to mark the beginning of the next item.

Terragrunt now preserves commas inside nested list and object expressions when parsing assume_role blocks, allowing configurations containing array attributes to be processed correctly.

Thanks to @Rahul-Kumar-prog for contributing this fix!