globalSettings should not require authentications

[mschipperheyn]

Is your feature request related to a problem? Please describe.
In multi vendor scenarios, and I imagine others as well, you might want to configure certain client side functionalities based on a configuration that you want to manage in the UI, ie not .env. The globalSettings is basically the ideal query for that but it requires authentication. I'm not entirely sure why that is the case.

Describe the solution you'd like
We need some kind of serverSettings style query that allows us to load customFields through a query that doesn't require authentication

Describe alternatives you've considered
I've considered offering this a plugin for htis. But this imho is really a basic concern that Vendure should offer.