Room migration of Online Books

[gouri-panda]

This is a subtask for #3102 . Write migration test and new database test for FetchDownloadEntity.

Should be done:

• A kind of generic and abstract accessor to access Room data

• Secure the Room DB is created properly at start (if it is not easy to create on the fly) if necessary (first installation or migration context)

• The data structure and accessor to the online books (based on what exists in ObjectBox)

• Link with the existing code around the online books(disconnect this from ObjectBox)

• Write the automated tests (Unit tests and maybe one UI test) for that new Room code (adapt what exists for ObjectBox)

• Write the migration function (for the data) from the ObjectBox online books DB to the Room DB

• Write automated tests for that migration function

• FetchDownloadEntity (Responsible for online Book/zim lists that the user can download) https://github.com/kiwix/kiwix-android/blob/e2c901bf22034ea891c29ce12bc5793df7eccf52/core/src/main/java/org/kiwix/kiwixmobile/core/dao/entities/FetchDownloadEntity.kt

[kelson42]

Here we should see how to better deal with libkiwix. We should seek an agreement before starting coding.

[kelson42]

I think the best way is here to not store anymore the online library (so retrieve it time to time), but just to make requests directly to the online service using the libkiwix. @mgautierfr you confirm? If "yes", I believe we still don't have a service generating the URL to request based on a filter, right?