Refactor sample app to deploy and run against real AWS

[whummer]

Refactor sample app to deploy and run against real AWS.

Summary of changes:

• Adjust IAM policies to grant access to resources
• Adjust ARNs to match real AWS
• Allow specifying a custom API Gateway endpoint in the UI

Screenshot from running against real AWS:

[whummer]

Work in progress.. Still need to look into the failing test

Update: tests passing now ✅

[whummer]

FYI - Should be fixed, going to merge @baermat 👍