feat!(PCGR): move sample params to samplesheet

[HomoPolyethylen]

this PR moves sample-specific parameters for PCGR to the samplesheet.
Params moved:

• tumor_site
• tumor_purity
• tumor_ploidy

This is a breaking, backwards-incompatible change, as the moved params are no longer supported as pipeline parameters (via CLI or params file).

closes #87

---

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 - have you followed the pipeline conventions in the contribution docs
• If necessary, also make a PR on the nf-core/variantprioritization branch on the nf-core/test-datasets repository.
• Make sure your code lints (nf-core pipelines lint).
• Ensure the test suite passes (nextflow run . -profile test,docker --outdir <OUTDIR>).
• 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).