Update tool/sync_ruby to match the new pathname.rb scheme

* Also run it for pathname.rb
* [ci skip]
Update documentation in tool/sync_ruby.

* [ci skip]
Sort paths in tool/globals_2_1_0.rb.

* [ci skip]
Refactor tool/sync_ruby a bit.

* Perfect occasion to use abort
* Stricter version validation
* Splat array in locals instead of indexing
* [ci skip]