Add versions - apprepository-controller

[antgamdia]

Description of the change

This PR adds the --version command to kubeops

Besides, it also adapts the code to the latest cobra boilerplate, so that all of our binaries are similar.

Benefits

Our binaries will properly display their version

Possible drawbacks

N/A

Applicable issues

• related Add --version to all of our binaries #3429

Additional information

Testing with:

DOCKER_BUILDKIT=1 docker build -t kubeapps/apprepository-controller:dev --build-arg "VERSION=$(git rev-parse HEAD)" -f cmd/apprepository-controller/Dockerfile .

docker run  docker.io/kubeapps/apprepository-controller:dev ./apprepository-controller --version