feat: notification center (#1612)

Co-authored-by: Pranav <pranav@chatwoot.com>

app/javascript/dashboard/i18n/default-sidebar.js

@@ -8,11 +8,13 @@ export const getSidebarItems = accountId => ({
       'inbox_conversation',
       'conversation_through_inbox',
       'contacts_dashboard',
+      'notifications_dashboard',
       'settings_account_reports',
       'profile_settings',
       'profile_settings_index',
       'label_conversations',
       'conversations_through_label',
+      'notifications_index',
     ],
     menuItems: {
       assignedToMe: {
@@ -31,6 +33,13 @@ export const getSidebarItems = accountId => ({
         toState: frontendURL(`accounts/${accountId}/contacts`),
         toStateName: 'contacts_dashboard',
       },
+      notifications: {
+        icon: 'ion-ios-bell',
+        label: 'NOTIFICATIONS',
+        hasSubMenu: false,
+        toState: frontendURL(`accounts/${accountId}/notifications`),
+        toStateName: 'notifications_dashboard',
+      },
       report: {
         icon: 'ion-arrow-graph-up-right',
         label: 'REPORTS',