Stream kubeadm progress logs

[tstromberg]

At the moment, there can be 20-25 seconds with no updates via JSON. This can cause a bad user experience, as noted by folks using minikube in an embedded environment.

We at least used to stream the kubeadm output to glog, but we should also make it available via JSON.

[tstromberg]

/cc @priyawadhwa

[medyagh]

simmilar to #9091 (but not same)

[medyagh]

however picks this task up this will require us to implement exec Command's Start for our Command Runner

here in the code we have
https://github.com/medyagh/minikube/blob/7bc81b1cbdae09aa2cdae46e377e4a8cc333f343/pkg/minikube/command/command_runner.go#L55

	c := exec.CommandContext(ctx, "/bin/bash", "-c", fmt.Sprintf("%s init --config %s %s --ignore-preflight-errors=%s",
		bsutil.InvokeKubeadm(cfg.KubernetesConfig.KubernetesVersion), conf, extraFlags, strings.Join(ignore, ",")))
	if _, err := k.c.RunCmd(c); err != nil {

https://github.com/medyagh/minikube/blob/7bc81b1cbdae09aa2cdae46e377e4a8cc333f343/pkg/minikube/bootstrapper/kubeadm/kubeadm.go#L229

which means we wait for command to Finish then we print the logs

but we can use golan'gs exec.Start()
and then wait for it

https://golang.org/pkg/os/exec/#Cmd.Start

This task might need us to add Start to our Own Command Runner Interface
which currently is

type Runner interface {
	// RunCmd runs a cmd of exec.Cmd type. allowing user to set cmd.Stdin, cmd.Stdout,...
	// not all implementors are guaranteed to handle all the properties of cmd.
	RunCmd(cmd *exec.Cmd) (*RunResult, error)

	// Copy is a convenience method that runs a command to copy a file
	Copy(assets.CopyableFile) error

	// Remove is a convenience method that runs a command to remove a file
	Remove(assets.CopyableFile) error
}

[medyagh]

@spowelljr

[spowelljr]

/assign