Trigger deployments on CFN StackSet updates

[tmclaugh]

As a developer an update to a CFN StackSet file will trigger an update when the deployment workflow is run.

Currently for StackSet resources in CloudFormation stacks we pass an S3 URL to the TemplateURL property. On top of that we need to manually sync these template files to that S3 bucket. An ideal workflow would ensure that:

1. A change to a StackSet template causes an update when an affected repo's deployment workflow is run and invokes CloudFormation.
2. Template files do not require manual syncing.

[tmclaugh]

Deployed some changes which look good so far.

[tmclaugh]

Need to add some of the enhancements in aws-gha-integration

[tmclaugh]

add some enhancements