SECRETS: Store quotas in a per-hive configuration structure
    
    Adds two new structures to hold the quotas and associate a quota with a hive.
    
    This is just an internal change for now, but will allow us to read quota
    configuration from per-hive sections later.
    
    Reviewed-by: Simo Sorce <simo@redhat.com>
    Reviewed-by: Fabiano Fidêncio <fidencio@redhat.com>