Do not duplicate logilab-database dependency

The logilab-database dependency seems to be a requirement for cubicweb and YAMS. It should be only one project that is responsible for the SQL translation, then it should be only one project which contains everything to generate the dedicated SQL.

The question is : Whether CubicWeb or YAMS should be responsible for the SQL translation?

For now cubicweb is the one, but it could be coherent that YAMS has to be.

Also, right now, while YAMS holds a dependency with logilab-database, it doesn't used it at all and test can runs without it.

This ticket is not implementation, only found a response for this question.