Add regenie/runl1 module

[lyh970817]

REGENIE is a C++ program for whole-genome regression modelling of large GWAS cohorts. This PR adds regenie/runl1, the module that gathers all level-0 outputs from the chunked Step 1 workflow and finishes Step 1, producing the standard prediction list and LOCO files consumed by regenie/step2.

This PR depends on the regenie/runl0 module in #11767.

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.
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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 regenie/runl1 --profile docker
    • nf-core modules test regenie/runl1 --profile singularity
    • nf-core modules test regenie/runl1 --profile conda