- /v3 doesn't exist if multi-cluster-management is disabled
- Use /v1/management.cattle.io.settings everywhere instead of /v3
- It now returns the public set of settings if retrieve with no auth, so
the store needs to remember that even though we loaded "all" of them
that wasn't really ALL of them so that the full list gets loaded after
auth.
- Use new x-api-cattle-auth header to determine authentication state if present
- Use SETTINGS.* constants consistently
- `brand` -> `ui-brand` for consistency
- `eula-accepted=true` -> `eula-agreed=<timestamp>` to match Ember