Add scds module

[cakirb]

This PR introduces a module for scds to address issue nf-core/scdownstream#118. Most of the code in this module is adapted from a local module in the scdownstream pipeline originally developed by @nictru (link).

While the module is functionally complete and ready for use, testing is currently impacted by a syntax issue in scds related to the xgboost version (see proposed fix: kostkalab/scds#9).

This PR should be retested once the scds package supports both older and newer xgboost versions, allowing compatibility across environments.

PR checklist

• 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
• If necessary, include test data in your PR.
• Remove all TODO statements.
• Emit the versions.yml file.
• Follow the naming conventions.
• Follow the parameters requirements.
• Follow the input/output options guidelines.
• Add a resource label
• 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:
  • For modules:
    • nf-core modules test <MODULE> --profile docker
    • nf-core modules test <MODULE> --profile singularity
    • nf-core modules test <MODULE> --profile conda
  • For subworkflows:
    • nf-core subworkflows test <SUBWORKFLOW> --profile docker
    • nf-core subworkflows test <SUBWORKFLOW> --profile singularity
    • nf-core subworkflows test <SUBWORKFLOW> --profile conda

[nictru]

Improve stub and version capture