ci: fix release flow in case of more than one package modified

[arnaud-moncel]

Fix CI release flow to publish each affected package individually on main

Replaces the single npx nx print-affected publish command in build.yml with a bash script that iterates over each affected project and runs npx nx run "$PROJECT:publish:package" for each one. The script exits early with a message when no packages are affected, and uses set -e to stop on the first failure.

^{Macroscope summarized 046fa5b.}