refactor: add minor collected changes

[AngryMaciek]

Summary

• adjusted conda envs: building for macOS
• cleaned the main MAPP env
• add 1s delay in SLURM status check (cluster delay)
• decreased snakemake verbosity
• adjusted conda frontend to mamba in snakemake envs building; included in the CI
• added --cores parameter to both the main execution script and the testscript
• adjusted testscript to run on macOS
• adjusted the create-main-configfile script to raise errors if incorrect paths provided in the config template; also if no path is provided for the STAR index a default dir will be generated under $HOME
• adjusted CI test 1 for MAPP to test the functionality presented point above
• linted the code
• tested with the small test triggered on both sciCORE and my personal Mac
• refactored README: more description (res, logs), moved and cleaned testing section up, adjusted ex. commands

[AngryMaciek]

@ajgruber

I have finally finished this round of corrections, I have edited the summary above in the PR description, please take a look at the bullet points.

Strangely enough, whenever I start a PR in this repo you are automatically and immediately asked for a revision. I don't know why this happens, thats the first time I see it and I cannot turn it off. Maybe you should try to turn it off in the repo settings to avoid getting spammed?