Add support for named in-memory database

[cayasso]

Support for named in-memory database:

file:memdb1?mode=memory&cache=shared

You can find more information here: https://www.sqlite.org/inmemorydb.html

The use case is more for testing multi-tenant apps, where you have a main database and you have your tenant databases, currently it seems like testing these type of apps are imposible or very complicated.