passCredentials is misleading and should be removed

[meln5674]

The Application field spec.source.helm.passCredentials is misleading. Its presence on the Application resource implies that it only affects that Application. Whether or not this is the intent, this is untrue, as it applies to all Applications which use the same dependency repositories in use by the Application in question. This creates hard-to-diagnose issues, and looking at the issues page, I'd wager there are about 6 open bugs caused in some part by this.

I would like to propose the following:

Because ArgoCD (and Helm) applies this flag at the repository level, not at the Application (chart) level, the flag ought to be present on the repository config, and the Application field should be deprecated and cause a warning (in the same way that, e.g. an excluded resource does).

Aside from doing fresh helm repo add in an isolated environment for each app, I cannot think of any other way around this, but perhaps someone else more clever than I can.