CACHE_REQ: Move result manipulation into a separate module
    
    This patch is preparing the field for coming up patches where new lookup
    logic will be added.
    
    Taking this into consideration let's move the result manipulation code
    into a separate module and focus purely in the lookups logic in the main
    module.
    
    Related:
    https://pagure.io/sssd/sssd/issue/3001
    
    Reviewed-by: Fabiano Fidêncio <fidencio@redhat.com>