Stand up integration tests for S3 and GCS

[JPZ13]

This ticket is two parts:

1. Standing up an S3 and GCS bucket in Pipekit infrastructure for testing
2. Adding integration tests to the Argo Workflows codebase that validate that reads/writes to S3 and GCS work as intended

We'll need @tico24 to stand up the infrastructure, provision any secrets needed, and add them to the appropriate secrets store (most likely the Github secrets on this repo)

From there, we're free to implement the tests that do the connection however we see fit. I know @Joibel and @tico24 have both mentioned that they would like to test workflows using Argo Workflows itself. I'll leave that decision on whether to do that in this PR to y'all

[tico24]

Oddly, I have a PR to add s3 buckets to our internal workflows instance already, so this is almost 'done'.

For GCS, I'll need... GCS please @JPZ13

[tico24]

s3 is now set up internally.

@Joibel will need various bits of internal access in order to use it though. Probably not sensible to document on this public repo.