Feature/icres based grns

[nicomaper]

This pull request contains the following:

• Update of the .gitignore file to include the correct matching for the output and error SLURM files.
• Changes to give the ACR files as a channel to the genome-wide and locus-based workflows, instead of as a string/value parameter. This will make it easier to implement the changes mentioned below to include the "iCREs-based MINI-AC" feature.
• Necessary script to run this "iCREs-based MINI-AC", including a process that executes a Python script to use the files with the iCREs annotated to their closest gene, to retrieve the coordinates associated with the genes of interest (input).
• The input gene sets of the example to run the test of this new feature.
• The corresponding example config file (and a small update on the previous one for the commented annotations, but no change to code)
• The corresponding documentation update to this new feature.
• Final update on the .gitignore file to avoid committing confidential files or files that are too large (iCREs BED files).

[hdbeukel]

Nicely done! Some minor comments only.