Add Prime registry push to staging

[mallardduck]

This will address: #113

[skanakal]

@mallardduck @diogoasouza Since this issue is affecting multiple customers, it might be a good idea to prioritize it. Would it be possible to get this merged soon?

[mallardduck]

@skanakal - This change is a priority, however it will not fix the root issue. The issue you are referring to is tracked here: rancher/rancher#50949 - it manifested because the image tags were not used by any charts actually in rancher/charts.

If that situation arises again (the tag is only used outside of rancher/charts), then the same issue will happen even if this is merged. Today, what happens is that when an image is found in a chart scripts in charts repo will sync it from Hub (or Prime staging) into Prime Registry.

Merging in this will only change where that script finds and syncs the image from, it does not address the root issue. So while this is a priority to fix, this alone will not prevent the issue if rancher/rancher#50949 from happening again.