feat: Replace close shortcut options for pinned tabs with a single menulist

This commit replaces the four separate checkboxes for close shortcut options for pinned tabs with a single menulist. This makes the UI more streamlined and user-friendly, as users can now easily select from a list of available options instead of having to check or uncheck multiple boxes.

The new menulist offers the following options:

- reset-unload-switch: Resets the tab if it was changed, otherwise unloads it.
- unload-switch: Unloads the tab if it was changed, otherwise does nothing.
- reset-switch: Resets the tab if it was changed, otherwise switches to it.
- switch: Switches to the tab.
- reset: Resets the tab.
- close: Closes the tab.

This provides a more comprehensive and flexible set of options for managing pinned tabs, making the experience more intuitive and customizable.

src/browser/components/preferences/zen-settings.js

@@ -1020,14 +1020,14 @@ Preferences.addAll([
     type: 'bool',
     default: false,
   },
-  {
-    id: 'zen.pinned-tab-manager.reset-pinned-tab-on-close-shortcut',
-    type: 'bool',
-    default: true,
-  },
   {
     id: 'zen.pinned-tab-manager.restore-pinned-tabs-to-pinned-url',
     type: 'bool',
     default: true,
   },
+  {
+    id: 'zen.pinned-tab-manager.close-shortcut-behavior',
+    type: 'string',
+    default: 'switch',
+  },
 ]);