Clean up cosmo_inference folder #235

Currently, the sp_validation/cosmo_inference folder contents contains many scripts with functionalities that overlap with cs_util and sp_validation, as well as plotting notebooks that should be living in the sp_validation/papers directory. I propose to:

1. Clean up this directory by removing the obsolete scripts in the cosmo_inference/scripts subfolder
2. Clean up the cosmo_inference/cosmocov_config folder since we are no longer using Cosmocov
3. Move the notebooks to their relevant parent directories
4. Check that the structure of the folder and the scripts within adhere to the Snakemake framework in sp_validation/workflow/rules/inference.smk.