Implement atomic acl updates on cisco ios

The cisco ios generator currently removes the acl and redeploys it. This action impacts traffic and potentially permanently disrupts administrative access to the device during the process (unless explicitly designed otherwise). There is no atomic configuration application mechanism as for other networking devices (e.g. Juniper's `commit` or Cumulus Linux's `nv config apply`).

I propose a change to the generator which should be enabled by a switch/option `atomic` and create atomic ACL list updates in cisco ios the following way:

- deploy the new acls (temporarily) to `${acl}-new` and `ipv6-${acl}-new`
- change `traffic-filter` and `access-group` to the new (temporary) acl identifiers
- deploy the new acls to `${acl}` and `ipv6-${acl}`
- change `traffic-filter` and `access-group` to the regular acl identifiers `${acl}` and `ipv6-${acl}`
- remove the new acls `${acl}-new` and `ipv6-${acl}-new`