feat: Cache CI-built cloud-provider-kind Docker image

[nialdaly]

Summary

• Currently the cloud-provider-kind-cloud-provider:latest Docker image is built after checking out the cloud-provider-kind repo and running:

sudo bash -c 'NET_MODE=kind docker compose up -d'

• Once this image is built, it can be cached (using a composite action) for subsequent workflow runs to use.

[markgoddard]

Did you see this approach? https://docs.docker.com/build/cache/backends/gha/#using-dockerbuild-push-action

Unsure if it's better, and it would require building the image first, using the cache parameters.

[nialdaly]

I've used that in previous places, the change would be as you say to pre-build the image first building it using docker-compose!

[markgoddard]

It would be nice to extract this into an action to reduce duplication, but I won't block on that.