Add filtering of VEP annotated VCF files using bcftools/view

[famosab]

This adds bcftools/view to enable filtering the VCFs for specific patterns. Mostly to filter through VEP annotation.

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
• Make sure your code lints (nf-core pipelines lint).
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• 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).

[d4straub]

LGTM!