postgres: allow wheel users to auth to pg as any db user

[foodelevator]

NOTE: Requires postgres 16, but main is currently on postgres 15.

Allows users in the wheel group to authenticate to postgres as any user, while not removing the normal peer authentication ability.
A basically identical setup works for me on my machines (that run postgres 16).

Makes e.g. psql -U sso work.

[github-actions]

OpenTofu plan for dsekt-infra

Plan: 2 to add, 0 to change, 2 to destroy.

OpenTofu used the selected providers to generate the following execution
plan. Resource actions are indicated with the following symbols:
-/+ destroy and then create replacement

OpenTofu will perform the following actions:

  # module.nixos_install["ares"].module.nixos-rebuild[0].null_resource.nixos-rebuild must be replaced
-/+ resource "null_resource" "nixos-rebuild" {
!~      id       = "*******************" -> (known after apply)
!~      triggers = { # forces replacement
!~          "store_path" = "/nix/store/wvbh3vlzdwi354jj6dgnw1726ipz90p5-nixos-system-ares-24.05.20240830.6e99f2a" -> "/nix/store/0i864pyckmhp8f1ygi0v5l9x2ljjl4j8-nixos-system-ares-24.05.20240830.6e99f2a"
        }
    }

  # module.nixos_install["hades"].module.nixos-rebuild[0].null_resource.nixos-rebuild must be replaced
-/+ resource "null_resource" "nixos-rebuild" {
!~      id       = "*******************" -> (known after apply)
!~      triggers = { # forces replacement
!~          "store_path" = "/nix/store/lrs513bq9cjzmqwbpawnl2kbnzc02bfk-nixos-system-hades-24.05.20240830.6e99f2a" -> "/nix/store/sckbdvjz0w0rj93w2mbg13vw678v6w8h-nixos-system-hades-24.05.20240830.6e99f2a"
        }
    }

Plan: 2 to add, 0 to change, 2 to destroy.

📝 Plan generated in Create OpenTofu plan #49