Workshop environment helper stack

[athewsey]

Issue #, if available: N/A

Description of changes:

Add a helper stack (in AWS SAM, deployable to S3-hosted CloudFormation+assets) for automated deployment of the solution into temporary environments (mainly aimed towards workshops and similar).

The Textract Transformer Pipeline today deliberately:

• Is implemented in CDK (which helps keep it modular for customization)
• Avoids deploying SageMaker notebook infrastructure (because customers may have existing setups with a range of configurations)

...And both decisions come with good reasons but make initially deploying the stack to experiment a little more complex. This helper stack provides a more automated way to get started, at the expense of making a few too many simplifying assumptions for brownfield environments.

Testing done:

Spun up & ran through in test environment

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