Add HDL rg module

[lyh970817]

HDL estimates SNP heritability and pairwise genetic correlation from GWAS summary statistics. This PR upstreams hdl/rg, which estimates pairwise genetic correlation from two canonicalized GWAS summary statistics files with an HDL LD reference panel.

The HDL fixtures used by these tests are available on the merged nf-core/test-datasets modules branch from nf-core/test-datasets#1932.

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.
• Broadcast software version numbers to topic: versions - See version_topics
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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:
  • For modules:
    • nf-core modules test hdl/rg --profile docker
    • nf-core modules test hdl/rg --profile singularity
    • nf-core modules test hdl/rg --profile conda