UMI extraction

[mirpedrol]

Description of feature

Create a module for extracting UMIs form sequencing reads

[mirpedrol]

After having a look at this issue, I realized it's not the best solution, as nf-core modules can only use python scripts as templates, what would require modifying the original code, or using the script inside a container, what would require the authors to release this script as a standalone python package.
For now, I think the best option is to keep it as a local module.