Catch OCI version errors and return them

[manno]

Refers to #1606

The module we use would panic if version wasn't set or invalid.

With this change, an explicit version is not required for OCI charts. The module will reach out to the registry and fetch the tags and will resolve them to a version.

		// If empty, try to get the highest available tag
		// If exact version, try to find it
		// If semver constraint string, try to find a match

https://github.com/helm/helm/blob/release-3.14/pkg/downloader/chart_downloader.go#L144-L175

[manno]

Alternatively I can change the code, so I can mock the registry client. I'd then delete these test, because they mostly test the helm code. I would then add tests to check if the client is initialized and if error wrapping works.

[weyfonk]

As discussed offline, despite the DNS and OCI registry dependencies, LGTM. As noted in the test driver, this nicely documents a few use cases.