Promisify all model.tsx functions

[mtfranchetto]

Description

Before introducing react-query we have handled every request to an API using callbacks (see model.tsx).
This is not a best practice for many reasons, and most of all, callbacks cannot be used with react-query, as they library expects a Promise from the data loader function.

Following what has been done in #175 we should replace all model.tsx functions still using callbacks, and make them return Promises, which can then be used by react-query for an efficient data retrieval.