Good secrets management in Eka

[ic4-y]

I thinks it's imperative that we think of managing secrets from the beginning. There are multiple dimensions to this I see intuitively. At least these two here

1. We might support something like sops to populate secrets in eka.toml. This would be different from using sops-nix to populate secrets on NixOS systems / home configurations . But maybe we can find a smart way to hook into the first layer of sops to make things like sops-nix superfluous? Not sure.

2. Builder endpoints like I proposed in Refine CLI core structure #1 might need authentication of various kinds, from simple HTTP authentication to JSON webtokens, to other tokens (like biscuit tokens).

Let's keep track of what we need / want to implement and in what order via this issue.