[Task] Create project volumes to save databases data

What should be done

When using the Lenra CLI we might want to keep the development data between two tests. When creating many apps we also want to separate one app data from another one.

Add the possibility to keep the data when wanted by the user. It should be a new option to add this to the terminal context.

A shortcut should be added to the dev mode (K as keep ?).

Technical recommandation

Create two folders in the .lenra forder to keep the data only for the given app.

Ecological concerns

By default the stop command remove de volumes.