add image release workflows

[pdabelf5]

Proposed changes

These workflows can we called individually or called from other workflows. They trigger the copy-images.sh script with the relevant config for the target registry.

Examples

oss-release.yml:

inputs.gcr_release_registry: true
inputs.ecr_public_registry: true
inputs.dockerhub_public_registry: true
inputs.quay_public_registry: true
inputs.github_public_registry: true
inputs.source_tag: edge
inputs.target_tag: 3.5.0
inputs.short_target_tag: 3.5
inputs.dry_run: false

plus-release.yml:

inputs.nginx_registry: true
inputs.gcr_release_registry: true
inputs.gcr_mktpl_registry: true
inputs.ecr_mktpl_registry: true
inputs.az_mktpl_registry: true
inputs.source_tag: edge
inputs.target_tag: 3.5.0
inputs.short_target_tag: 3.5
inputs.dry_run: false

retag-images.yml:

inputs.source_tag: <stable_md5>
inputs.target_tag: edge
inputs.dry_run: false

Checklist

Before creating a PR, run through this checklist and mark each as complete.

• I have read the CONTRIBUTING doc
• I have added tests that prove my fix is effective or that my feature works
• I have checked that all unit tests pass after adding my changes
• I have updated necessary documentation
• I have rebased my branch onto main
• I will ensure my PR is targeting the main branch and pulling from my branch from my own fork