NethCTI: Refactor operator favorites to remove phonebook permission dependency

[viktec]

Description

Currently, saving favorites requires the “Manage private contacts” permission. As a result, users cannot save favorites unless they have level 1 permission to manage private contacts.

Favorites should be independent of phonebook permissions and available to users with phonebook read access.

Steps to reproduce

1. Enable phonebook access for a user.
2. Disable permission to manage private contacts.
3. Log in to the CTI as that user.
4. Mark an operator as favorite.
5. Close and reopen the CTI.

Expected behavior

The operator remains in the user's favorites without requiring contact-management permissions.

Actual behavior

The favorite is removed after reopening the CTI. Saving it sends a POST request to /api/phonebook/create, which returns:

{
  "message": "forbidden"
}

The current workaround is to grant level 1 permission for private contact management.