Draft: Nsswitch custom resource

This is my attempt at the accumulator-pattern for chef-resources. Valuable sources, that helped me understand how to do this were https://docs.chef.io/infra_language/cookbook_execution/#with_run_context and https://blog.dnsimple.com/2017/10/chef-accumulators/

❗ 💩 ❗ This is not compatible with jessie as of now. 💩 ❗ 💩

❗ Since this approach does not use attributes anymore, fixes in gsi-sys and other depending cookbooks are required.