add tests for the bk2 files

[bpinsard]

write tests that will:

• [ ] check that the durations of the bk2 files (number of frames or steps) matches the durations in the tsv (there might be ms diffs).
• [ ] ...

[hyruuk]

Write a qc_test.py file that :

1. Generates a quality_control.tsv file
2. Crawls across the full dataset
3. For each file, add an entry to the TSV file and test for :
   • broken bk2
   • early-stop
   • Missing MRI/events.tsv/bk2 files
   • Missing bk2 pointer in events.tsv
   • Get durations from events.tsv and bk2 file