[REFACTOR] Move sources in Python SDK to sub package

[georgeh0]

Currently sources.py is a single module with all sources. We want to convert it a sub package, so that later we can add sub modules within it - good for modularization.

Similar to #1028 (which is for targets)

[Davda-James]

will try to do this one

[badmonster0]

thanks @Davda-James ! you are on fire 🔥🔥