[dev-ratio] simplified toolsheet structure, and modified the subworkflows accordingly

[suzannejin]

Hello! Just restructured the toolsheet into the following three blocks: 1- differential analysis 2- correlation analysis 3- enrichment analysis Also the subworkflows were modified accordingly to accomodate for the new block structure.

In the coming days I will update the modules from these three blocks as well (maybe first as local modules), and then change the arguments from the toolsheet accordingly.

PR checklist

• [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
• [ ] If necessary, also make a PR on the nf-core/differentialabundance branch on the nf-core/test-datasets repository.
• [x] Make sure your code lints (nf-core lint).
• [x] Ensure the test suite passes (nf-test test main.nf.test -profile test,docker).
• [ ] Check for unexpected warnings in debug mode (nextflow run . -profile debug,test,docker --outdir <OUTDIR>).
• [ ] 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).