Go module, bump versions of k8s libs, rework of the Informer for namespaces (more suitable), rework of secretGenerator

[achoimet]

Hello,

I moved the project to go module because we use it in my enterprise. Bumped some librairies.

Also I reworked the Informer because the one used was not really suitable for add cases like described in here. In doubt I Switched to a SharedInformer.

I reworked the SecretGenerator in a way that if there is no argument for one cloud provider, it won't create an empty secret and try to refresh it later.
I think there is more to do to refactor tests to reflect this change, because I needed to switch from 4 expected secrets to zero in several tests cases.

Also I change your Dockerfile for a multi build dockerfile with distroless base image but it was just for me because your image is lighter.

Anyway thanks for your work, I am now able to pull ECR images in newly created namespaces (with refresh setted at 1mn) with custom serviceAccountName.

[mahnoorfirdous]

Thank you so much for this excellent PR. While I'm trying to build the image though, I get the error from the go get -d command. It returns with a non-zero exit code. Any guesses as to why?