Proposal: add freshpod as an addon

[ahmetb]

I'd like to propose a new addon: https://github.com/GoogleCloudPlatform/freshpod/

What:

freshpod listens to the docker image events from the host docker.sock and deletes Pods running on Minikube when their images are updated.

Why:

This add-on vastly improves the refactor-build-run cycle on Minikube for me.
I can simply run a command to docker build my app when any of my .py files are updated:

$ find . -name '*.py' | entr docker build -t myapp .

and freshpod automatically kills pods running the myapp:latest image (with ~1s downtime at most). Therefore,
I think freshpod this solves in an elegant way by eliminating the steps such as having to run a
kubectl delete pods -l app=foo every time after rebuilding an image on Minikube’s docker-engine.

How: I propose we should bundle this add-on with Minikube as disabled-by-default.
It's written in Go and has minimal mem/CPU requirements. It uses watch/streaming APIs from
kube-apiserver and the docker engine, therefore has minimal load footprint. This way someone
can install Minikube and run this to start rolling:

minikube addons enable freshpod

If you support this idea, please hit 👍 , otherwise I'd love to hear concerns about it.

[r2d4]

Added in #2423