Add process selector for single core jobs

[matthdsm]

This PR adds a selector for single core, low resource jobs such as CUSTOM_DUMPSOFTWAREVERSIONS, Multiqc and the samtools qc steps

PR checklist

• This comment contains a description of changes (with reason)
• CHANGELOG.md is updated
• If you've fixed a bug or added code that should be tested, add tests!
• Documentation in docs is updated

[codecov]

Codecov Report

Merging #1630 (d87e8d6) into dev (65cb765) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##              dev    #1630   +/-   ##
=======================================
  Coverage   64.91%   64.91%           
=======================================
  Files          56       56           
  Lines        6428     6428           
=======================================
  Hits         4173     4173           
  Misses       2255     2255           

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