Integrate starlib and bazel-skylib

[jordemort]

Extend the API to allow extra parameters to be passed to the Starlark() constructor that specify additional Starlark libraries to make available in the interpreter.

starlib

https://github.com/qri-io/starlib

These look to be written in Go and will need to be compiled into the extension.

bazel-skylib

https://github.com/bazelbuild/bazel-skylib/tree/main/lib

Some of this is bazel-specific and won't be useful, but the path manipulation and type introspection stuff is ❇️

This stuff is in Starlark, so we probably just want to vendor the files we want and exec them upon request.