Longread mapping creation

[opetryk]

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/bactmap branch on the nf-core/test-datasets repository.
• Make sure your code lints (nf-core lint .).
• Ensure the test suite passes (nextflow run . -profile test,docker).
• 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).

This pull request has following changes:

1. Added new module bcftools/stats
2. Added new subworkflow longread_mapping
3. HARDCODED a possibility to generate index file with bcftools filter (should be reviewed other possibilities in the future) - provided --write-index=tbi into args
4. Updated schema file
5. updated nextflow config with new parameters
6. provided basic minimal test to the new subworkflow

Things that should be done:

1. docker/conda profiles should be added do be able to execute tests/pipeline
2. nf-test tests should be finished and successfully executed
3. create test nextflow.config file and provide path to in in nf-test.config
4. subworkflow should be verified if it executes correctly
5. Sources (storage, ram etc) should be limited for test/stub run to be able to run it locally (new profile can be created)

links to test files were taken from nf-core/modules repository