Prepare v2.0

[jacquesbh]

• Move the test application to Sylius 1.8, update all dependencies, even change some dependencies.
• Disable APIs on test application.
• Update github workflows and remove now useless Circle CI
• Prepare 2.0 changing the version, adding UPGRADE-2.0.md and so on.
• Run PHP CS Fixer on all source code.
• Update the local infrastructure and the Makefile to have a better developper experience.

The test of the container is disable since it's broken by Doctrine.