[sam] AWS SAM Policies inside CDK

## :rocket: Feature Request

### General Information

* [X] :wave: I may be able to implement this feature request

* [ ] :warning: This feature might incur a breaking change

### Description

The AWS SAM IAM Policy Templates should exist in the aws-SAM module so users can easily translate their SAM Templates into CDK

### Proposed Solution

Naive approach, manually copy the templates.
Smart approach, maybe find a way to load the policy definitions from the aws-sam repository.

Start by reviewing the aws-SAM module and the AWS SAM policy template definitions in the aws-sam repository. Compare the manual-copy and dynamic-loading approaches, then define how the templates should be exposed so SAM templates can be translated into CDK. Done means the policy templates are available through the module and covered by the project's relevant tests.

Written by the indexing model from the issue text.