feat: Add the ability to mention team in private message (#11758)

This PR allows agents to mention entire teams in private messages using
`@team_name` syntax. When a team is mentioned, all team members with
inbox access are automatically notified. The scheme changes can be found
[here](https://github.com/chatwoot/prosemirror-schema/pull/34).

---------

Co-authored-by: iamsivin <iamsivin@gmail.com>
Co-authored-by: Sivin Varghese <64252451+iamsivin@users.noreply.github.com>
Co-authored-by: Sojan Jose <sojan@pepalo.com>

app/services/messages/mention_service.rb

@@ -19,14 +19,33 @@ class Messages::MentionService
   end
 
   def mentioned_ids
-    @mentioned_ids ||= message.content.scan(%r{\(mention://(user|team)/(\d+)/(.+?)\)}).map(&:second).uniq
+    user_mentions = message.content.scan(%r{\(mention://user/(\d+)/(.+?)\)}).map(&:first)
+    team_mentions = message.content.scan(%r{\(mention://team/(\d+)/(.+?)\)}).map(&:first)
+
+    expanded_user_ids = expand_team_mentions_to_users(team_mentions)
+
+    (user_mentions + expanded_user_ids).uniq
+  end
+
+  def expand_team_mentions_to_users(team_ids)
+    return [] if team_ids.blank?
+
+    message.inbox.account.teams
+           .joins(:team_members)
+           .where(id: team_ids)
+           .pluck('team_members.user_id')
+           .map(&:to_s)
+  end
+
+  def valid_mentionable_user_ids
+    @valid_mentionable_user_ids ||= begin
+      inbox = message.inbox
+      inbox.account.administrators.pluck(:id) + inbox.members.pluck(:id)
+    end
   end
 
   def filter_mentioned_ids_by_inbox
-    inbox = message.inbox
-    valid_mentionable_ids = inbox.account.administrators.map(&:id) + inbox.members.map(&:id)
-    # Intersection of ids
-    mentioned_ids & valid_mentionable_ids.uniq.map(&:to_s)
+    mentioned_ids & valid_mentionable_user_ids.map(&:to_s)
   end
 
   def generate_notifications_for_mentions(validated_mentioned_ids)