Transform the Build into a Pipeline

[squakez]

While reviewing #4024 I realized we may need to revisit the way we are generating, builiding and publishing an application. At the moment, this is a "static" series of tasks. We need to change them into a Pipeline and possibly let the user to specify which tasks to execute in its pipeline. As soon as we have the Pipeline we can also consider to skip it entirely, substituting it with any other external pipeline (ie, Tekton) which could be in charge to take over the build/publishing process.

This work would simplify #1656 and enable #682 and will allow the user to provide some additional external task (ie, to scan dependencies from vulnerabilities).

[squakez]

Done in #4384