Add gene biotypes to interactive volcano plots

[SusiJo]

PR checklist

Only takes effect if a gtf file is provided as input and if the field gene_biotype is available in the attributes of the gtf file.

• [x] 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 pipeline conventions in the contribution docs
• [x] Make sure your code lints (nf-core lint).
• [x] Ensure the test suite passes (nextflow run . -profile test,docker --outdir <OUTDIR>).
• [x] Usage Documentation in docs/usage.md is updated.
• [x] Output Documentation in docs/output.md is updated.
• [x] CHANGELOG.md is updated.
• [ ] README.md is updated (including new tool citations and authors/contributors).