modules: move options to the top

This greatly improves readability and makes it easier to discover options.

This commit was genereated by running the following script inside the
repo root dir:

#!/usr/bin/env ruby

def transform(src)
  return false if src.include?('inherit options;')

  success = false

  options = nil
  src.sub!(/^  options.*?^  }.*?;/m) do |match|
    options = match
    "  inherit options;"
  end
  return false if !options

  src.sub!(/^with lib;\s*let\n+/m) do |match|
    success = true
    <<~EOF
      with lib;
      let
      #{options}

    EOF
  end

  success
end

Dir['modules/**/*.nix'].each do |f|
  src = File.read(f)
  if transform(src)
    puts "Changed file #{f}"
    File.write(f, src)
  end
end

modules/onion-services.nix

@@ -7,19 +7,7 @@
 { config, lib, pkgs, ... }:
 
 with lib;
-
 let
-  cfg = config.nix-bitcoin.onionServices;
-  nbLib = config.nix-bitcoin.lib;
-
-  services = builtins.attrNames cfg;
-
-  activeServices = builtins.filter (service:
-    config.services.${service}.enable && cfg.${service}.enable
-  ) services;
-
-  publicServices = builtins.filter (service: cfg.${service}.public) activeServices;
-in {
   options.nix-bitcoin.onionServices = mkOption {
     default = {};
     type = with types; attrsOf (submodule (
@@ -52,6 +40,19 @@ in {
     ));
   };
 
+  cfg = config.nix-bitcoin.onionServices;
+  nbLib = config.nix-bitcoin.lib;
+
+  services = builtins.attrNames cfg;
+
+  activeServices = builtins.filter (service:
+    config.services.${service}.enable && cfg.${service}.enable
+  ) services;
+
+  publicServices = builtins.filter (service: cfg.${service}.public) activeServices;
+in {
+  inherit options;
+
   config = mkMerge [
     (mkIf (cfg != {}) {
       # Define hidden services