Add PU tag to Read Groups for all mapping methods

[IdoBar]

Add PU tag to Read Groups for all mapping methods.
This is an improvement to PR #656

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 - add to the software_versions process and a regex to scrape_software_versions.py
• If you've added a new tool - have you followed the pipeline conventions in the contribution docs
• If necessary, also make a PR on the nf-core/eager branch on the nf-core/test-datasets repository.
• Make sure your code lints (nf-core lint .).
• Ensure the test suite passes (nextflow run . -profile test,docker).
• Usage Documentation in docs/usage.md is updated.
• Output Documentation in docs/output.md is updated.
• CHANGELOG.md is updated.
• README.md is updated (including new tool citations and authors/contributors).

[github-actions]

Hi @IdoBar,

It looks like this pull-request is has been made against the IdoBar/eager master branch.
The master branch on nf-core repositories should always contain code from the latest release.
Because of this, PRs to master are only allowed if they come from the IdoBar/eager dev branch.

You do not need to close this PR, you can change the target branch to dev by clicking the "Edit" button at the top of this page.

Thanks again for your contribution!

[jfy133]

Looks good to me! I've just made a pull request into your new patch again, so you have the correct CHANGELOG file to update. Let me know if you need help updating the changelog.

[jfy133]

Ok, now you have the CHANGELOG for the next release,

please edit the CHANGELOG file, and under 2.3.1dev [unreleased] and fixed, add something like

#655 - Updated read groups for all mappers to allow proper GATK validation

(or w/e).

Finally, please add your name and github handle to the README under 'additional contributors' :).

Note all links above point to your patch branch of your fork, so you can edit those directly!

[apeltzer]

Thank you @IdoBar