Improve how the code is shared with the container.

[wkania]

Prior to the PR there was one volume for the code. All the containers shared the same path for the vendor. Switching was made with the symlink. There was a problem with including volume with code, so the vendor symlink would be only on the container and not on the host. Git was reporting the symlink file as a change. To fix that, there are multiple volumes and none of them expose vendor in the code directory.

What can be done:

• symlink is not needed anymore because each vendor is on its own container,
• maybe there is a way to include code as one volume.