Public docker registry

[andreacfm]

We want to store the backend and frontend images on a publicly accessible docker registry (possibly on Github).

• Create the required scripts (or makefile) to build and push the images

For example:

make build-all
make build-backend
make build-and-push-all

• Consider allowing the build-and-push script to be executed also from a github action (manually triggered)
• Keep the image names consistent (otlp-blueprint-{imagename})

Notes:

• When pushing we want to create a new tag version + update the latest tag.