Stop depending on rules_pkg through the federation. (#259)
Stop depending on rules_pkg through the federation. (#259)

- while the federation code is in flux, this will mean less churn for skylib
- rules_pkg is only needed by developers for making a distribution, so this won't impact users.
- when we develop a new federation model, we can re-depend the right way.
bazelbuild/bazel-skylib,bazelbuild/bazel-skylib,bazelbuild/bazel-skylib