Implement a "blhc" task to analyze build logs for potential problems

As a debusine user, I can run blhc on the build logs of Debian packages (build logs that I manually submitted or build logs generated as a side effect of a package build that happened on debusine).

Useful links:

• https://manpages.debian.org/unstable/blhc/blhc.1p
• blhc job in https://salsa.debian.org/salsa-ci-team/pipeline/

Progress

• Design the interface for the "blhc" task
• Implement the Task class in Python
• Implement the ansible role to setup the worker