SQL generator handling generalization/specialization

[ademait]

Is your feature request related to a problem?

When we define inheritance classes, the SQL generator generates the classes for each define class (parent and children, even when parent is abstract).

Describe the solution you'd like

To define whether we want the inheritance to be represented in the database using generalization or specialization strategies.

Describe alternatives you've considered

Additional context

[jcabot]

The idea would be to open a pop-up with some configuration questions, at least including the desired general strategy for dealing with inheritance (only supertypes, only subtypes, keep them all). Sure, this could also change for each generalization but that would be already a more future request