[FEATURE] Ability to pass/set environment variables on registry creation

[armenr]

Is your feature request related to a problem or a Pull Request

Basic problem

Scope of your request

Ability to set environment variables on the registry container

Describe the solution you'd like

Something that looks like this/enables this would be ideal:

apiVersion: ctlptl.dev/v1alpha1
kind: Cluster
name: k3d-armenr-local
product: k3d
k3d:
  v1alpha5Simple:
    servers: 1
    agents: 1
    image: rancher/k3s:v1.32.3-k3s1
    registries:
      create:
        name: cache-registry
        image: cache-registry:latest
        host: "0.0.0.0"
        hostPort: "5007"
        volumes:
          - /var/run/docker.sock:/var/run/docker.sock
          - /home/armenr/.aws:/home/appuser/.aws:ro
          - /home/armenr/.docker:/home/appuser/.docker:ro
          - /home/armenr/Development/some-project/sas/_k8s/registry-cache:/var/lib/registry
        env:
          - AWS_PROFILE=some-project-dev
          - HOME=/home/appuser
      config: |
        mirrors:
          "*":
            endpoint:
              - http://cache-registry:5000

Describe alternatives you've considered

Run/create the custom cache container outside of k3d's scope entirely, and manage additional "start" steps before starting the k3d cluster...just to get around the limitation of not being able to set environment variables on the registry in the k3d/ctlptl config itself.