bash: add logoutExtra option

tests/modules/programs/bash/default.nix

@@ -1,3 +1,4 @@
 {
+  bash-logout = ./logout.nix;
   bash-session-variables = ./session-variables.nix;
 }

tests/modules/programs/bash/logout-expected.txt

@@ -0,0 +1,4 @@
+# -*- mode: sh -*-
+
+clear-console
+

tests/modules/programs/bash/logout.nix

@@ -0,0 +1,22 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+{
+  config = {
+    programs.bash = {
+      enable = true;
+
+      logoutExtra = ''
+        clear-console
+      '';
+    };
+
+    nmt.script = ''
+      assertFileExists home-files/.bash_logout
+      assertFileContent \
+        home-files/.bash_logout \
+        ${./logout-expected.txt}
+    '';
+  };
+}