ETL (msa+templates) should be separated from inference

Dear all,

for our application, we need the possibility to run ETL (in this case MSA+templates) separate from inference.

At the moment this is not supported, but having a look at the code it should be a relatively simple thing to add a flag to stop the pipeline after the ETL is done. And if I understand correctly, the pipeline already resumes from the right point when use_precomputed_msa is used (although for some reason, the templates are always recomputed, but that does not take too long).

Is such a feature already implemented? Maybe it's planned? If not, are you accepting PRs? I would be glad to contribute some code, rather than manually hacking my private version.

Andrea.