feat(Migrator): add step option

[MaximeMRF]

❓ Type of change

• [ ] 🐞 Bug fix (a non-breaking change that fixes an issue)
• [ ] 👌 Enhancement (improving an existing functionality like performance)
• [x] ✨ New feature (a non-breaking change that adds functionality)
• [ ] ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

As discuss in the pr #940 here is the step option for the migration rollback.

At the moment if you use step option with batch option too, the batch option will not work and only the effect of the step option will count. Another behavior is when you use a negative number it will rollback all migrations.

What's your opinion about theses behaviors ?

[thetutlage]

@MaximeMRF Can you please document it as well?

[MaximeMRF]

Yes i will do it