**What this PR does / why we need it**:
Visibility rules allow dependency control. The rules currently in
place make all targets public, to override the default state of
private. This PR removes public visibility from kubectl code. It
uses specially named pacakge groups to identify "bad" dependencies on
kubectl code for later refactoring or removal.
**Which issue this PR fixes**
First in a series of PRs to address kubernetes/community#598
**Release note**:
```release-note
NONE
```
Currently attach and the editor do not share the same logic for saving
and restoring the terminal, and are not suitable for nesting (when the
caller wants to create something, attach, and then delete something when
the attach is over). This commit moves the interrupt protection logic
to a util package and supports nesting interrupt handlers.
Contains the following fixes for Windows users of kubectl edit:
* Defaults to notepad as the default Windows editor
* Uses CRLF line endings
* Ensures a file lock is freed