Add Publish OS Image github action

[darkowlzz]

Publish OS Image action is a manually triggered action with parameters
GOARCH, WHAT, RELEASE, USER for building and publishing OS container
image.
It is a developer automation action for building and publishing OS
images easily.

NOTE: Must set CR_PAT and CR_HOST in the github repo secrets for
the image push to succeed.

Tested the action in a fork for building various images and publishing to
github container registry and manually verified that the published images
boot and are usable.
Refer:

• https://github.com/darkowlzz?tab=packages
• https://github.com/darkowlzz/ignite/actions/runs/273283567

Image build for alpine fails due to missing alpine.tar file. This can be
fixed in the makefile separately.
Opensuse image build fails because the base image for it isn't public and
can't be pulled, logs. Works with correct RELEASE value, was using latest.

[darkowlzz]

Closing for #717