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/store/modules/conversations/helpers/specs/actionHelpers.spec.js

@@ -0,0 +1,12 @@
+import { isOnMentionsView } from '../actionHelpers';
+
+describe('#isOnMentionsView', () => {
+  it('return valid responses when passing the state', () => {
+    expect(isOnMentionsView({ route: { name: 'conversation_mentions' } })).toBe(
+      true
+    );
+    expect(isOnMentionsView({ route: { name: 'conversation_messages' } })).toBe(
+      false
+    );
+  });
+});