Migrate to KMM setup

[wesleydonk]

Goal
Streamline updating (internal) apps by using KMM shared modules for both Android and iOS.
At the moment the project is split up between two components:

• core (with submodules)
• ui

We can start to rewrite the core to a KMM setup, which currently already uses Flow<T> for Android. So it should not be a large setup. If the core is done, sharing with other platforms should be a breeze.

Steps

• Replace database with SqlDelight.
• The fetcher module should be supporting KMM where both platforms use their own POV dependency based on a shared interface.