Module to download CDD databases

[Ales-ibt]

This module was developed to download and process the CDD databases necessary to run rpsblast from the FTP site of the NCBI.

PR checklist

• [X] This comment contains a description of changes (with reason).
• [X] If you've added a new tool - have you followed the module conventions in the contribution docs
• [X] Remove all TODO statements.
• [X] Emit the versions.yml file.
• [X] Follow the naming conventions.
• [X] Follow the parameters requirements.
• [X] Follow the input/output options guidelines.
• [X] Add a resource label
• [X] 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:
    • [X] nf-core modules test blast/cdddownloader --profile docker