global/xonsh: init

This is temporary until Xonsh in home-manager is landed

modules/global/xonsh.nix

@@ -0,0 +1,20 @@
+{ config, pkgs, ... }:
+let
+  cfg = config.programs.xonsh;
+in
+{
+  programs.xonsh = {
+    enable = true;
+    extraPackages =
+      p: with p; [
+        parallel-ssh
+        cfg.package.xontribs.xonsh-direnv
+      ];
+    config = ''
+      xontrib load direnv
+
+      if $TERM != "dumb":
+          execx($(starship init xonsh))
+    '';
+  };
+}