Get IaC production-ready: add test suite to Pulumi code

[bsweger]

Add a test suite to the Pulumi code in the hubverse-infrastructure repo so that we can make updates to it with a higher degree of confidence.

Definition of done:

• hubverse-infrastructure contains unit tests for the modules that create our S3 and IAM AWS resources
• hubverse-infrastructure has a GitHub workflow that runs the test suite
• PRs cannot be merged until the tests complete successfully

Some background info on Pulumi unit testing: https://github.com/Infectious-Disease-Modeling-Hubs/hubverse-infrastructure/tree/bsweger/add-model-output-transforms/hubverse-transforms