Publish container image of the server during ci

[duhizjame]

Images of server getting pushed as: ghcr.io/agile-lab-dev/io.whitefox.server to ghcr

on any PR the related image is pushed, on main branch we also publish "latest" tag

[tmnd1991]

before this PR I do not need to add any change but simply run:

./gradlew build -Dquarkus.container-image.build=true

and I get a locally tagged image as both:

io.whitefox/server                                  3bd642c
io.whitefox/server                                  latest

that works just fine.
Should we then not simply do something like docker push on the ci?

Also I would do this only on main branch for now