feat: Add a view for mentions (#3505)

- Added a new table mentions for saving user mentions
- Added a filter conversation_type in the API
- Added a view to see the mentions

app/javascript/dashboard/components/layout/config/sidebarItems/conversations.js

@@ -12,6 +12,8 @@ const conversations = accountId => ({
     'conversations_through_label',
     'team_conversations',
     'conversations_through_team',
+    'conversation_mentions',
+    'conversation_through_mentions',
   ],
   menuItems: [
     {
@@ -22,6 +24,13 @@ const conversations = accountId => ({
       toolTip: 'Conversation from all subscribed inboxes',
       toStateName: 'home',
     },
+    {
+      icon: 'mention',
+      label: 'MENTIONED_CONVERSATIONS',
+      key: 'conversation_mentions',
+      toState: frontendURL(`accounts/${accountId}/mentions/conversations`),
+      toStateName: 'conversation_mentions',
+    },
   ],
 });