Added workflows publishing the 'master' container image

[jpkrohling]

The script that is used for this workflow is the same we had before with Travis. It works locally when setting the username/password vars and I did add the same secrets to this repository. I believe this will work, but we'll only know when this gets merged.

Resolves #715

Signed-off-by: Juraci Paixão Kröhling juraci@kroehling.de

[jpkrohling]

This uses the branch's name instead of latest, in line with how we used to do before moving to GitHub Workflows.

jaeger-operator/.travis.yml

Lines 102 to 107 in 7664ef3

	- stage: deploy
	name: "Publish latest image"
	env:
	- OPERATOR_VERSION="${TRAVIS_BRANCH}"
	script:
	- "./.travis/publish-images.sh"

We could change the new .github/workflows/publish-images.yaml to also publish the master images under the latest tag, but I'd do it in a follow-up PR, I'm not 100% sure this PR here will work on the first attempt.

[jpkrohling]

@pavolloffay would be the right reviewer, as he's the author of the linked issue, but not sure he is available to review as he is at EclipseCon this week. @kevinearls, would you like to review this one instead?

[kevinearls]

@jpkrohling I'll check this afternoon, although I don't really have much background in this.

[kevinearls]

LGTM