Add supported types for input variables

Add support for IAM Role and other supported input types to SSM documents:


with current StringType, input variables for IAM roles cause errors when the role is used in the document.

Start by locating the StringType handling for SSM document input variables and identify how supported input types are represented. Verify the IAM Role case and other supported types against the repository's existing behavior; done means role-valued inputs no longer cause errors when used in an SSM document.

Written by the indexing model from the issue text.