🚚 move nf-core modules in nf-core subfolder

[bunop]

PR checklist

This PR will place all external nf-core dependencies in a nf-core subfolder. This will made easier maintain custom modules

Closes #22

• This comment contains a description of changes (with reason).
• If you've fixed a bug or added code that should be tested, add tests!
• If you've added a new tool - have you followed the module conventions in the contribution docs
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• Remove all TODO statements.
• Emit the versions.yml file.
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• Use BioConda and BioContainers if possible to fulfil software requirements.
• Ensure that the test works with either Docker / Singularity. Conda CI tests can be quite flaky:
  • PROFILE=docker pytest --tag <MODULE> --symlink --keep-workflow-wd --git-aware
  • PROFILE=singularity pytest --tag <MODULE> --symlink --keep-workflow-wd --git-aware
  • PROFILE=conda pytest --tag <MODULE> --symlink --keep-workflow-wd --git-aware