chore: fix parallelism in library compilation

[diegomarquezp]

This PR introduces a new approach to confirm the libraries of the current variant 2.0.0 are compilable. The approach is as follows:

• We define a job matrix based on alphabet letters for parallelization. Unfortunately, we need to explicitly declare outputs for each of the letters, but this is the official recommendation.
• We create parallel jobs running mvn compile on libraries starting with ${letter}
• The results are aggregated in a final step that prints the result

Total job duration: ~2 minutes
Example output:

Follow up:

• Link this job to CI dashboard