[fix] bringing back fname_presuffix and fixing copyfiles functions

[djarecka]

Acknowledgment

• I acknowledge that this contribution will be available under the Apache 2 license.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Summary

fixing copyfiles function:

• bringing back fname_presuffix function that is used in one block (it was removed in Testing for windows on Azure Pipelines and Travis #232)
• adding more tests

Checklist

• All tests passing
• I have added tests to cover my changes
• I have updated documentation (if necessary)
• My code follows the code style of this project
  (we are using black: you can pip install pre-commit,
  run pre-commit install in the pydra directory
  and black will be run automatically with each commit)