DRAGEN: new module ROH Metrics

[Just-Roma]

• CHANGELOG.md has been updated

• There is example tool output for tools in the https://github.com/ewels/MultiQC_TestData repository or attached to this PR
• Code is tested and works locally (including with --lint flag)
• docs/README.md is updated with link to below
• docs/modulename.md is created
• Everything that can be represented with a plot instead of a table is a plot
• Report sections have a description and help text (with self.add_section)
• There aren't any huge tables with > 6 columns (explain reasoning if so)
• Each table column has a different colour scale to its neighbour, which relates to the data (eg. if high numbers are bad, they're red)
• Module does not do any significant computational work

Merging:

• merging this PR would require updates in dragen/dragen.py and multiqc/utils/search_patterns.yaml
  in PR1911, PR1913, PR1914, PR1915. But not in the dragen/utils.py, because it is the same. The main file must be also included, of course.

[your-highness]

For some python versions there seem to be some LINT errors which I can not really explain. Help wanted.