Support for StackAuth / Neon Auth

[itsezc]

Neon's new Authentication service (based on StackAuth) also can be self deployed via this operator as they are tightly coupled services.

[bittermandel]

It's unfortunate Neon Cloud selected StackAuth for their auth stack, considering it's very young, mixed license and basically zero documentation for self-hosting at scale.

To our benefit, Neon itself only expects a JWT with certain scopes and audience. So we'll more than likely keep the operator agnostic to what system you run, as not to force people use StackAuth instead of their existing Auth system, which for us is Ory.