add rocky to list of rhel-based distros for configuration defaults

[mrichins]

Description

Found that when trying to use this cookbook while experimenting with rocky linux it fails for a null value being passed to a resource (I.e. its name value). This PR just fixes the case where a node's platform is rocky

Context

When using the library methods for getting default values for the osquery_daemon, osquery_config_path, osquery_packs_path and osquery_file_group there is a switch statement on the nodes ohai defined platform value.

And so for any platform outside of centos , ubuntu, redhat, and amazon distributions there is no value passed to the underlying resources such as here

While it is possible to override the functions to variables when using the cookbook resource directly, doing so does not appear to override the rest of the methods internally and so I've just updated the functions to provide the same response for rocky as it would for any of the other distributions.

Additionally it might be nice to default to a sane value in cases where the platform does not match, but I am not sure what a goo value for that might be, or if it would be better to just throw a named error.