nerdctl for Windows.

[mook-as]

This implements a stub nerdctl bianry on Windows that execs into the (correct) WSL distribution.

This is in support of #566.

TODO:

• Figure out how do deal with volume mounts (nerdctl run -v foo:bar)
• Figure out how to do nerdctl build from Linux.

[mook-as]

I believe both building (from linux) and doing volumes will require doing arg parsing in the nerdctl stub (to figure out where the paths are for arguments), and are best done in a follow-up. So I'm going to mark this as ready for review for now, assuming we'll do follow-ups.

For now, Windows should be able to do nerdctl build . (but only using relative paths).

[mook-as]

Note that I dropped f2093ca because it turned out that broke nerdctl run; we need to be in the correct WSL distro (mount namespace) to do that because nerdctl touches files directly, and not over the socket.

[ericpromislow]

mook-as-win-nerdctl $ golint ./...
cmd/k3s.go:1:1: package comment should be of the form "Package cmd ..."
cmd/k3s_kubeconfig.go:1:1: package comment should be of the form "Package cmd ..."
cmd/kubeconfig.go:1:1: package comment should be of the form "Package cmd ..."
cmd/root.go:1:1: package comment should be of the form "Package cmd ..."

Assuming we want our go code to be clean

[mook-as]

Hmm, golint appears to be deprecated; it seems to recommend staticcheck as a replacement, and that's fine with that code.

Also, note that you're linting code that is just moved, and no changes were made to it…