* Add rules to the test_deps target.
Likely needed for anyone doing integration tests using skylib.
* Default public visibility and only tag things that are private.
Most notably, this renames/moves a few important identifiers:
//:skylark_library.bzl -> //:bzl_library.bzl
skylark_library -> bzl_library
SkylarkLibraryInfo -> StarlarkLibraryInfo
This version is hash-based (implemented on top of a dictionary) and doesn't suffer the performance problems of the current version. It will eventually replace the old one after a deprecation period.