This means we no longer have to individually hard-code the `kops set`
fields, however we use the "language" we're now demonstrated.
We add tests to ensure we have parity with our existing (hard-coded)
setter logic.
We don't call klog.InitFlags yet, because that will cause a flag
redefinition error until we get everyone to stop using glog. That
will happen when we update to k8s 1.13.
We still need the reflect helpers, but we allow for clients to
register their own pretty-printers, which avoids the package
dependency for our pretty-printer. We register our pretty printers in
an init function in the relevant package (in this case,
upup/pkg/fi/printers.go)
Fix#5551