Updated cleaning methodology to clean correct files for viralrecon

[victor5lm]

PR checklist

• This comment contains a description of changes (with reason).
• Make sure your code lints (black and flake8).
• If a new tamplate was added make sure:
  • Template's schema is added in templates/services.json.
  • Template's pipeline's documentation in assets/reports/md/template.md is added.
  • Results Documentation in assets/reports/results/template.md is updated.
• CHANGELOG.md is updated.
• README.md is updated (including new tool citations and authors/contributors).
• If you know a new user was added to the SFTP, make sure you added it to templates/sftp_user.json

PR description

Closes #311.
Currently, depending on the protocol defined when running the viralrecon pipeline, .sorted.bam files should be deleted or not. To handle this situation, the following changes are suggested by this PR:

1. services.json has a new field: clean_script, by which it will be possible to indicate if a specific cleaning script should be used to clean files associated with that specific service. For now, this is only useful for viralrecon, but could be used for other services in the future.
2. In relation to this, within assets/utils, a new script called viralrecon_clean.py is stored. This script is indicated in services.json, and the clean module will use this auxiliary script to get the service's protocol from the viralrecon_params.yml file and, depending on this, delete or not the appropriate BAM files.
3. The clean module is accordingly adapted to this. Given each one of the services associated with the resolution, this module will check if an auxiliary cleaning script exists for each of these services, and then will perform the cleaning depending on whether the service has an auxiliary file associated or not. If it does, the auxiliary script will be employed. If no auxiliary script exists, the files and folders to be deleted/purged will be the ones indicated in the clean --> folders/files field of services.json.

[saramonzon]

Cool!