Support attachments for behave-parallel

#### I'm submitting a ...
- [ ] bug report
- [x] feature request
- [ ] support request => Please do not submit support request here, see note at the top of this template.

#### What is the current behavior?
Behave parallel doesn't support attachment into enviroment.py (before step, after step ....)

#### What is the expected behavior?
Support use attachments (screenshot, file, log) for behave-parallel as well as at behave

#### What is the motivation / use case for changing the behavior?
consistency and better way for debugging

Inizia individuando l’integrazione di behave-parallel e confrontandola con il supporto esistente di behave per gli attachments. Traccia il modo in cui vengono gestiti gli attachments provenienti dagli hook di environment.py come before e after steps, quindi verifica che screenshot, file e log compaiano correttamente nei risultati Allure generati per le esecuzioni parallele.

Scritto dal modello di indicizzazione a partire dal testo della issue.