Move observation plan generation scripts out of the repository #8
Description
The create_observation_plan.py script contains a lot of code that is duplicated or should belong in the skaworkflow repository.
It's not clear to me how much, but certainly the observation/HPSO permutations heuristics and supporting methods. I do not know if plan creation for the number of days should go into skaworkflows as well, or if the specific calculations and runners for numbers of days should stay in the script, and that's what we use the leftovers of the script for. I am not convinced we need a CLI for SKAWorklfows (having previously removed one).