chore(refactor): Improve conversation permission filtering (#11166)

1. Add permission filter service to separate permission filtering logic
from conversation queries
2. Implement hierarchical permissions with cleaner logic:
   - conversation_manage gives access to all conversations
- conversation_unassigned_manage gives access to unassigned and user's
conversations
- conversation_participating_manage gives access only to user's
conversations

---------

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

app/controllers/api/v1/accounts/conversations_controller.rb

@@ -48,7 +48,7 @@ class Api::V1::Accounts::ConversationsController < Api::V1::Accounts::BaseContro
   end
 
   def filter
-    result = ::Conversations::FilterService.new(params.permit!, current_user).perform
+    result = ::Conversations::FilterService.new(params.permit!, current_user, current_account).perform
     @conversations = result[:conversations]
     @conversations_count = result[:count]
   rescue CustomExceptions::CustomFilter::InvalidAttribute,