Databases reset feature for testing

[AymDev]

Testing the migration requires manually resetting the target database to delete migrated data.

Solution: Especially if #4 is implemented, target connections databases could reset themselves in development, if a SQL script is provided.

UPDATE 2021-05-17: Tests using a database can extend AbstractDbalTestCase. It still resets manually. A test has been made to use an in-memory SQLite database but the DBAL platform does not support foreign key constraints and is incompatible with the foreign key feature as mentionned in ForeignKeyBeforeTask.

Leaving open until https://github.com/doctrine/dbal/issues/4288 is fixed