Respect existing cluster pull secret configuration

[everettraven]

Catalogd currently requires pull secrets to be passed through the Catalog resource's spec.source.image.pullSecret field. The Secret referenced in that field must be in the same namespace as catalogd is deployed in (typically catalogd-system). Catalogd should be able to identify any existing pull secrets and automatically resolve them for a registry that is referenced in the spec.source.image.ref field.

[joelanford]

Catalogd should be able to identify any existing pull secrets

Can you explain this a bit more? What do you mean by "existing pull secrets", and in what cases would catalogd be expected to use them when they are not explicitly referenced in the Catalog object?