modules: integration tests for different registries
There are many different kinds of OCI registry implementation out there. We'd like our modules implementation to be compatible with as many as possible. This implies some checks to ensure that our code works when them, hence adding integration tests against those registries.
Some examples, in no particular order:
See also the detail in #2843 (which is a dupe of this issue)
As part of this work we would also add a page to cuelang.org that summarises the state/level of support for each.
Just adding a comment as a reminder, that we should include in this suite of tests intentionally broken servers for behaviour that we claim to support via https://pkg.go.dev/cuelabs.dev/go/oci/ociregistry and verify the behaviour via cue/load and friends.