DEV: Add missing keyboard shortcut on cheatsheet

PR #23387 introduced a new keyboard shortcut to archive private
messages, but the new shortcut wasn’t added to the keyboard shortcuts
cheatsheet.

app/assets/javascripts/discourse/app/components/modal/keyboard-shortcuts-help.js

@@ -150,6 +150,12 @@ export default class KeyboardShortcutsHelp extends Component {
             keys1: [SHIFT, "a"],
             keysDelimiter: PLUS,
           }),
+          archive_private_message: buildShortcut(
+            "actions.archive_private_message",
+            {
+              keys1: ["a"],
+            }
+          ),
         },
       },
       navigation: {

config/locales/client.en.yml

@@ -4163,6 +4163,7 @@ en:
         print: "%{shortcut} Print topic"
         defer: "%{shortcut} Defer topic"
         topic_admin_actions: "%{shortcut} Open topic admin actions"
+        archive_private_message: "%{shortcut} Toggle archive private message"
       search_menu:
         title: "Search Menu"
         prev_next: "%{shortcut} Move selection up and down"