chore: Add job for sorald-buildbreaker

[slarse]

Fix #3788

This PR adds a workflow job that runs https://github.com/spoonlabs/sorald-buildbreaker on Spoon, and fails the build if the changed lines (relative to master) contains any repairable violations. Here's an example of where it finds a violation in the diff: https://github.com/INRIA/spoon/pull/3912/checks?check_run_id=2543019363#step:3:123. Note that the final commit in this PR, which just removes the artificial rule violation, causes the build to go green!

Currently, it's a separate job, but once we deem buildbreaker to be stable enough we can simply incorporate it into the extras job by adding this step:

      - name: Run Sorald Buildbreaker
        uses: SpoonLabs/sorald-buildbreaker@35c1a784848bd3182cfcc8a584cff90560fa6371 # dev version
        with:
          source: 'src/main/java'
          ratchet-from: 'origin/master'

Next steps are to improve the stability of buildbreaker, and also identify what else we want buildbreaker to do. How should it present rule violations (current presentation is cryptic to the uninitiated, to say the least)? Should it propose a patch to fix the violation? Etc, etc.

Important: sorald-buildbreaker is very much experimental at this point. I would not exclude the possibility of spurious failures that have nothing to do with the PR. Please ping me if it fails on any PR such that I can investigate.

[slarse]

Current failure is a bug in sorald-buildbreaker, see SpoonLabs/sorald-buildbreaker#46

[slarse]

The new violation is found by Sonar, but there's obviously some problem with the ratchet as buildbreaker does not try to repair it.

Back to the drawing board!

Edit: It was a problem with relative source paths, see SpoonLabs/sorald-buildbreaker#49

[slarse]

Ah, it finally works, the newly introduced rule violation is detected: https://github.com/INRIA/spoon/pull/3912/checks?check_run_id=2543019363#step:3:123

[monperrus]

Excellent, thanks a lot @slarse