StepAction hub/catalog resolver support

[vdemeester]

Feature request

Make sure we can pull StepAction from the hub/catalog resolver, and also that we can configure the default "catalog" for them (similar to Task and Pipeline)

Use case

This is kind-of a follow-up of tektoncd/catalog#1218 (and part of #7424)

[chitrangpatel]

Initiated discussion with ArtifactHub: artifacthub/hub#3677 (comment)

[chitrangpatel]

This is now implemented: artifacthub/hub#3677 (comment)
The staging is here: https://staging.artifacthub.io/packages/search?kind=23

@vdemeester can we close this issue now?

We have support for StepActions on our GitHub catalog, Tekton Bundles and ArtifactHub.

[vdemeester]

@chitrangpatel if we have tests already that get some stepaciton using the hub resolvers, yes we can 😉