add first pass of action to sync hubverse data to cloud backend

[bsweger]

Cloud-enabled hubs will need a github action that syncs data in the following hub folders to cloud storage (as specified in the hub's admin config):

• hub-config
• model-metadata
• model-output (model-output data should sync to a "raw" cloud storage directory/folder so we can save its original state before doing any subsequent transforms)

Here is an example that we've been testing with: https://github.com/Infectious-Disease-Modeling-Hubs/hubverse-cloud/blob/main/.github/workflows/publish_to_s3.yaml

• role-to-assume should be derived from a combination of the Hubverse AWS account number + hub name
• bucket name in the aws s3 sync commands should be derived from the hub's admin config

[bsweger]

Got something working in the hubverse-cloud repo: https://github.com/Infectious-Disease-Modeling-Hubs/hubverse-cloud/blob/main/.github/workflows/publish_to_s3.yaml

Will PR this to the hubverse-actions repo.

The action is safe for adding to hubs that don't have any cloud config set up in admin.json. If it doesn't detect the cloud config, it will skip the steps that sync data to S3.