feat: Relax location_header_to_url path handling

[joonas]

When testing this library against Google Cloud Artifact Registry, I noticed the upload URL they return when obtaining a session id differs from the spec.

Instead of returning a Location: as specified in the OCI Distribution spec:

/v2/<name>/blobs/upload/<reference>

GCP Artifactory Registry returns the following Location: header:

/artifacts-uploads/namespaces/<gcp-project-id>/repositories/<artifact-registry-repository>/uploads/<some-hash>

I would like to propose relaxing the location_header_to_url code slightly to allow the use of this returned header, which does seem based to be on a perhaps slightly "looser interpretation" of what the spec says under POST then PUT:

Upon success, the response MUST have a code of 202 Accepted, and MUST include the following header:

Location: <location>

The MUST contain a UUID representing a unique session ID for the upload to follow. The does not necessarily need to be provided by the registry itself. In fact, offloading to another server can be a better strategy.

Optionally, the location MAY be absolute (containing the protocol and/or hostname), or it MAY be relative (containing just the URL path). For more information, see RFC 7231.

To further motivate this, 'd like to point out that the oras-go handles this without any issue, so it would seem reasonable to try to align the behavior between the two libraries in this regard.