feat: replace custom sync script with skopeo

[Mossman1215]

custom sync script was failing to work and was generating a lot of toil

summary of the changes is captured in the docs change copied below

Sync an image

Images are synced by specifying source repositories in sync-ghcr.yml for github and sync-ecr.yml for ecs/ecr

check skopeo documentation for more details https://github.com/containers/skopeo/blob/main/docs/skopeo-sync.1.md

quay.io:
  tls-verify: true
  images:
    fedora/fedora-coreos:
      - stable

on pull requests skopeo sync runs with --dry-run

full sync runs when merged to main

[ardrigh]

(YOLO Fridays. jk.) This looks good and we need to give this a run.

[ardrigh]

Using override to bypass not implemented check presubmit-signed-images-are-signed