Addition of generic registry

[johnmehan]

Added a generic registry allowing k8s-image-swapper to be used with registries that use username/password.

[towolf]

Also interested in having this in.

[towolf]

@johnmehan we would like to deploy a simple local Docker registry without auth. Would that also be supported?

[InputObject2]

From my testing, it looks like this forces defining every source registry and will error out on any images are not from a registry in the list. It also forces adding creds to all of them. @johnmehan I've PR'd your repo with an additional modification to enable using anonymous copies (both on source and destination) and also without defining creds for everything.

@towolf While waiting for this to be merged eventually I pushed an image to inputobject2/k8s-image-swapper:v1.5.9-noauth that I'm using without issue in my homelab.

[johnmehan]

@InputObject2 I've merged your changes. Thanks!

[estahn]

Can we rename this to targetRegistryClient to stay consistent with the config?

[InputObject2]

@estahn this PR might also close #29 and #30

[rattboi]

@estahn would love to see this get merged. I think I'm going to need to build this w/ the PR and run my own container in the meantime.

[rattboi]

hi @estahn , I'm curious if you've found time to review this.

[mrclrchtr]

I'm also interested in this change

[krx252525]

Here's a rough draft of this branch rebased against the latest changes/dependabot updates: #819

[mittalsuraj18]

Do we know when this will be merged @estahn ?
After the new changes regarding pull request that dockerhub has put up, this will help a lot so that we can authenticate with dockerhub with a single pro account while pulling images and then caching to our relevant aws ecr or gcp registries.