Build from source on Android

[janicduplessis]

Currently source is not shipped on Android, I think it would be nice to have a way to compile from source, similar to what is possible to do with react-native.

• Ship source as part of npm package alongside prebuilt artifacts
• Add docs on how to configure source build

Source builds make it easier to debug issues as well as test fixes directly in apps.

[mrousavy]

I have created a PR for this here: #1837