S3 FDML catalog

[lindholc]

This is a Catalog that gets datasets from FDML files in S3.

I wrote the catalog implementation a few months ago, but only recently had the inspiration on how to test it. I just threw all this together as a POC. We'll want to clean it up some.

s3mock, which we've used in the past, is no longer maintained. I've heard of testcontainers in other contexts, so I figured I'd give it a shot. I'm using the LocalStack module. (There's also a different S3Mock that works with testcontainers that might be worth exploring.) It's pretty slow to start up, so maybe we don't run these tests every time.

I'm curious how easily these tests run locally for you. I had to do some extra setup because I'm using colima, but I managed to have it all handled outside of the build. It looks like it just works in GHA.

[lindholc]

Consider switching from testcontainers to whale-tail.

[lindholc]

I wonder if s3proxy using in-memory mode would be a less complicated way to test this. It can be embedded, so there's no need for Docker.