* Add slurm::spank defined type to manage SPANK plugins
* Add plugstack_conf, plugstack_conf_d, purge_plugstack_conf_d parameters with defaults remaining the same
* Add spank_plugins parameter to allow defining slurm::spank resources
* Recursively manage plugstack.conf.d directory contents
* Rename slurm node and controller service resources to be specific to each role
* Remove unused template for auks plugin and add example usage to slurm::spank unit tests