feat(core): clear all notifications (#13144)

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

* **New Features**
* Added a "Delete All" option in the notifications list, allowing users
to mark all notifications as read at once.
* Introduced a header with a menu button in the notifications list for
easier access to actions.

* **Style**
* Updated notification list layout with improved structure, including a
header and a scrollable content area.

* **Localization**
* Added a new English localization string for the "Delete all
notifications" action.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/frontend/i18n/src/i18n.gen.ts

@@ -7778,6 +7778,10 @@ export function useAFFiNEI18N(): {
       * `Accept & Join`
       */
     ["com.affine.notification.invitation.accept"](): string;
+    /**
+      * `Delete all notifications`
+      */
+    ["com.affine.notification.delete-all"](): string;
     /**
       * `Tips`
       */

packages/frontend/i18n/src/resources/en.json

@@ -1948,6 +1948,7 @@
   "com.affine.notification.invitation-blocked": "There is an issue regarding your invitation to <1>{{workspaceName}}</1> ",
   "com.affine.notification.invitation": "<1>{{username}}</1> invited you to join <2>{{workspaceName}}</2>",
   "com.affine.notification.invitation.accept": "Accept & Join",
+  "com.affine.notification.delete-all": "Delete all notifications",
   "tips": "Tips",
   "Template": "Template",
   "com.affine.template-list.delete": "Delete Template",