The new version has slightly changed the structure of returned error
messages, so this includes some small compensating changes to avoid the
messages redundantly mentioning the same tag or digest twice.
Signed-off-by: Martin Atkins <mart@degeneration.co.uk>
This is a new implementation of go-getter's "Getter" interface intended
to support installing OpenTofu module packages from OCI Distribution
repositories.
Since this is currently only intended for OpenTofu's use it makes some
simplifying assumptions that would not be acceptable for an upstream
getter, but are okay for the limited way that OpenTofu's module installer
uses go-getter, which is already intentionally constrained and hidden
behind a simpler API so we can treat go-getter as purely an implementation
detail.
This commit only introduces the getter, without actually registering it
as available for use in the module package fetcher used by "tofu init",
and so this is effectively just a bunch of dead code. A later commit will
wire this in properly and introduce an end-to-end test to demonstrate that
it's properly integrated.
Signed-off-by: Martin Atkins <mart@degeneration.co.uk>
