* Move api/filesys to kyaml/filesys
* Add deprecated version of api/filesys with aliases to new code
* Use new kyaml/filesys package and update dependencies
* Migrate to kyaml/filesys and update dependencies
* Skip tests that break on Windows
The implementations in WNode are supposed to be thin,
as it will be removed once #2506 closes.
The change also makes some addjustments for the
upcoming flip of the enable_kyaml flag, pointing to
issue #3271.