Testting/add snapshots (#95)

* adapting tests and adding snapshots

* implement snapshot for all expected output files
Add test case for empty phenotype

* added snapshot for all workflows
added two test cases
    missing phenotypes should cause pipeline failing and no output file
    specify one phenotype should output only one output file

* Test if stderr error message is correct
    contains "missing required parameter"

* Replace manual assertions with snapshot

* exchange manual assertions with snapshot
    for "Should output all regenie lines"

* Added test with high threshold
    writes empty output file

* Add test case with no significant hits
    for additive GWAS
    pipeline should success
    filtered tophits are empty

* removed typo
update snapshots

* Change input format to vcf.gz for gene-based tests and update snapshots

* Add missing outdir directory

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Co-authored-by: Lukas Forer <[email protected]>
Co-authored-by: Sebastian Schoenherr <[email protected]>