Move api/filesys to kyaml/filesys (#3997)

* 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

kyaml/filesys/doc.go

@@ -0,0 +1,7 @@
+// Copyright 2019 The Kubernetes Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+// Package filesys provides a file system abstraction,
+// a subset of that provided by golang.org/pkg/os,
+// with an on-disk and in-memory representation.
+package filesys