[QA]: fix dataset-naming

[kitsudaiki]

QA

Description

Datasets are sometimes named data-set, sometimes data_set and sometimes dataset in the code. This is very inconsistent and has to be fixed. So it has to be renamed everywhere to dataset.

Acceptance Criteria

1. data-set and data_set are everywhere renamed to dataset
2. documentation was updated

Additional Information

Blocked by

How to test