feat(ocm): Add support for non-tar json component descriptor blobs

[8R0WNI3]

Fixes open-component-model/open-delivery-gear#204

Release note:

The Python OCM lib now features component descriptor blobs of non-tar type as well as json type too

[ccwienk]

LGTM overall — clean refactor, and the layers_count walrus bug fix is a nice bonus.

Two small notes:

• component_descriptor_from_tarfileobj (and the async raw_component_descriptor_from_oci) were public — did you check for external consumers? Happy to approve either way, just want to make sure it's on your radar.

• Minor readability nit in normalize_nulls:

  k: normalize_nulls(v) if v is not None else ([] if k in null_allowed_for else v)

  The else v arm silently keeps None for non-listed keys, which is correct but not immediately obvious. A short comment there would help a future reader.

[8R0WNI3]

component_descriptor_from_tarfileobj (and the async raw_component_descriptor_from_oci) were public — did you check for external consumers?

I did check but I could not find any external consumers.

The else v arm silently keeps None for non-listed keys, which is correct but not immediately obvious. A short comment there would help a future reader.

I have added a short comment on this :-)

[gardener-prow]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: ccwienk

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Details

Needs approval from an approver in each of these files:

• OWNERS [ccwienk]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[gardener-prow]

LGTM label has been added.

Details

Git tree hash: ce80f2d9c769fe532ff2ee82a1a1f9d9985e12ea