Add ibis integration

[cmungall]

https://ibis-project.org/

A lot of similarity in goals - provide a common abstraction layer over different backends. It seems to focus more on SQL/dataframe backends, but it seems no reason why mongodb etc could not be added.

Minimally we can add an ibis wrapper to give access to a wider range of backends. But we should explore the possibility of making ibis more of a first-class layer, possibly even replacing the existing Database/Collection/ResultSet data model, allowing linkml-store to focus on more linkml concerns, e.g. validation.