CI workflow update, documentation update; maintenance

• update CI workflow to run with modern simtools containers:
  • set env variables correctly for corsika and sim-telarray path
  • add downloading of corsika interaction tables steps (although at this point none of the examples is using corsika)
  • allow to run the workflows manually.
• add developer section to docu (as I forget these things)
• update pre-commit

Note that we also added the DB access variables as secrets to the simulation model project.