Decide whether to replace bazel-skylib

Context:

- Rules Authors SIG [meeting on 9 July 2024](https://docs.google.com/document/d/1YGCYAGLzTfqSOgRFVsB8hDz-kEoTgTEKKp9Jd07TJ5c/edit#heading=h.chsbc1d7wg17)
- Skylib is no [longer accepting FRs](https://github.com/orgs/bazelbuild/discussions/3)
- Docs are currently confusing: https://github.com/bazel-contrib/bazel-lib/issues/885

Now that this repo is under Linux Foundation in bazel-contrib, it's time for a fresh discussion of whether to remove our dependency on bazel-skylib and just fork it the rest of the way.

Why not to fork:
- duplicated effort
- Google's bug fixes in bazel-skylib won't be picked up here, and vice versa

Why to fork:
- when changes aren't accepted to skylib, it will be clear where you could put them instead
- this repo can remove a dependency, which is nice since it's near the root of the Bazel Module graph.

No files or tests are named. Start by reading the 9 July 2024 Rules Authors SIG notes, the bazel-skylib discussion, and issue #885; compare the case for removing the dependency with the case for forking it. Done means reaching and recording a decision with clear next steps for the confusing documentation.

Written by the indexing model from the issue text.