Provide a flag to also publish a `:latest` tag

[yoshuawuyts]

In bytecodealliance/sample-wasi-http-rust#52 we're calling a second instance of wkg-github-action to publish a :latest tag. This has the downside that it seemingly incorrectly encodes the version field when uploading the image - which should be set to the semantic version, but is hardcoded to latest.

Publishing a rolling latest tag alongside versioned artifacts is a common practice in the container world, and it would be convenient if wkg-github-action provided native support for this. Or alternatively have a way to separate the "version" annotation in the OCI image from the version we're publishing to the registry. Thanks!

cc/ @thomastaylor312 maybe you have opinions here?

[thomastaylor312]

So I am generally of the opinion that we shouldn't be publishing latest for interfaces since those are strictly versioned, which was the initial target here. wkg currently prints a WARN when fetching dependencies if it sees a tag that isn't valid semver specifically for this reason.

However, there is also the use case of publishing a component, which is exactly what the sample code you link does. In that case, I think following the best practice of updating latest is the correct thing to do.

So the question is do we try to enforce semver only in wkg if it is a WitPackage and if it is a component, we allow overriding just the tag it is pushed to OCI with?