Accept OCI manifests for indexing

[hdonnay]

This seemed simple enough, haven't check if there are other places where we want to accept other inputs.

Still need to update the openapi reference.

[ldelossa]

This is cool, and I like the idea. Only question is how do we want to communicate this to user? Do we simply say "make a json post with this mime type and we'll assume you are sending an oci manifest"? whats your thoughts here.

[hdonnay]

Yeah, I think we'd document the acceptable input types, and control them via the content-type header. The default would be the current state of things (assume it's our manifest format).

[ldelossa]

Cool, as a caveat we will have to reject any oci manifests where either do not contain a content descriptor, or contain a content descriptor without urls.

[mieliespoor]

Any indications on when this will see progress again? Merging this will greatly improve integrations.