astroid: add module

Astroid is a notmuch/gtk based MUA: https://github.com/astroidmail/astroid

modules/programs/astroid-accounts.nix

@@ -0,0 +1,33 @@
+{ config, lib, ... }:
+
+with lib;
+
+{
+  options.astroid = {
+    enable = mkEnableOption "Astroid";
+
+    sendMailCommand = mkOption {
+      type = types.str;
+      description = ''
+        Command to send a mail. If msmtp is enabled for the account,
+        then this is set to
+        <command>msmtpq --read-envelope-from --read-recipients</command>.
+      '';
+    };
+
+    extraConfig = mkOption {
+      type = types.attrs;
+      default = {};
+      example = { select_query = ""; };
+      description = ''
+        Extra settings to add to this astroid account configuration.
+      '';
+    };
+  };
+
+  config = mkIf config.notmuch.enable {
+    astroid.sendMailCommand = mkIf config.msmtp.enable (
+      mkOptionDefault "msmtpq --read-envelope-from --read-recipients"
+    );
+  };
+}