Enable the renovate config in this repo to be used outside of the adobe org

[justinedelson]

Is your feature request related to a problem? Please describe.

I would like to be able to reuse the renovate configuration from default.json in a repository that is not part of the adobe org. However, this does not work because the npmToken is contained in this file and renovatebot (correctly) refuses to decrypt this for git repositories outside of this org.

Note - overriding this configuration does not work; renovatebot always tries to decrypt the values from extended configurations.

Describe the solution you'd like

1. Extract everything except the encrypted token into a separate file (let's say core.json)
2. Change default.json to be

{
  extends: [
    'local>adobe/helix-shared:core'
  ],
  encrypted: {
     npmToken: '...'
  }
}

Then a repository outside of this org can have

{
  extends: [
    'github>adobe/helix-shared:core'
  ],
  ...more config...
}

And not run into encryption issues.

Describe alternatives you've considered

1. Copy/paste 😢
2. Move token to renovate.json5 -- this, however, would break backwards compatibility for repositories in the adobe org.

Additional context

Happy to submit a PR for this but wanted to first understand if it is desirable to have this configuration be reusable outside of this org.