This directory contains "image layout" directories, as described in this
specification:
    https://github.com/opencontainers/image-spec/blob/v1.0/image-layout.md

We use these in conjunction with the fake OCI registry implementation in
package fakeocireg as part of end-to-end testing the module installer's
"oci" source address scheme.

These fake repositories each contain valid metadata for some module packages,
though the module packages just contain placeholder configuration since this
is only intended for testing module package installation and not for testing
module evaluation.
