Leverage (or delete) the common key in values secrets

The umbrella chart sets up a values secret to feed into each helmrelease. Each values secret has 3 keys (overlays, common, defaults).

• Overlays: user provided "overlays" via <pkg>.values
• Defaults: things BB sets up by default for the package (all this stuff)
• Common: An empty key 🙃

I think the value of common would be things that are used for every chart, since they would be fed to every helmrelease. I can think of values that would fit here (networkPolicies, hostname/domain, istio.enabled, monitoring.enabled, ...). Currently these values are all just copy-pasted to the package specific files, but they could easily be shared everywhere.

The common key seems confusing and I would hope that it can either be deleted or utilized as described above to make the user experience better.