feat: Add support for search_conversations in copilot (#11520)

Earlier, we were manually checking if a user was an agent and filtering
their conversations based on inboxes. This logic should have been part
of the conversation permissions service.

This PR moves the check to the right place and updates the logic
accordingly.

Other updates:
- Add support for search_conversations service for copilot.
- Use PermissionFilterService in contacts/conversations, conversations,
copilot search_conversations.

---------

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

app/services/conversations/filter_service.rb

@@ -28,16 +28,6 @@ class Conversations::FilterService < FilterService
       :taggings, :inbox, { assignee: { avatar_attachment: [:blob] } }, { contact: { avatar_attachment: [:blob] } }, :team, :messages, :contact_inbox
     )
 
-    account_user = @account.account_users.find_by(user_id: @user.id)
-    is_administrator = account_user&.role == 'administrator'
-
-    # Ensure we only include conversations from inboxes the user has access to
-    unless is_administrator
-      inbox_ids = @user.inboxes.where(account_id: @account.id).pluck(:id)
-      conversations = conversations.where(inbox_id: inbox_ids)
-    end
-
-    # Apply permission-based filtering
     Conversations::PermissionFilterService.new(
       conversations,
       @user,

app/services/conversations/permission_filter_service.rb

@@ -8,9 +8,23 @@ class Conversations::PermissionFilterService
   end
 
   def perform
-    # The base implementation simply returns all conversations
-    # Enterprise edition extends this with permission-based filtering
-    conversations
+    return conversations if user_role == 'administrator'
+
+    accessible_conversations
+  end
+
+  private
+
+  def accessible_conversations
+    conversations.where(inbox: user.inboxes.where(account_id: account.id))
+  end
+
+  def account_user
+    AccountUser.find_by(account_id: account.id, user_id: user.id)
+  end
+
+  def user_role
+    account_user&.role
   end
 end