Firebase App Distribution setup

[andrzejchm]

• on each commit to open pr we build and distribute android and iOS version to testers and add a comment to the pr with a download link. Only approved testers can follow it, while others will receive 404. there should be a separate testers group on firebase set up for that

• on each commit to main branch, distribute app version meant for broader audience, interrested only in a working version of the app. there should be a separate testers group on firebase set up for that.

Each of those versions should have a changelog set up out of the last 5 commits