APK size optimization umbrella (remaining task: size comparison on PRs)

Examine APK size on release builds, should be as small as possible

Currently has some bloat in there

### (Optional) Anything else you want to share?

- there is an APK size comparison tool but it doesn't run all the time (yet) #16613
- there is proguard and release builds are set to optimize, but the proguard rules are currently not aggressive at all
- we are not testing release builds in CI so changing proguard settings is dangerous until fixed (tracking in #16625 )

So, idea is:

- test release builds in CI so changes to proguard get some validation
- #16635
- alter emulator test workflow to post release APK artifact for main merges (so we have current baseline size)
- future enhancement
- alter emulator test workflow to compare current posted main APK size with current release build size (ingesting compare size workflow logic...) and posting results (currently a comment, but as a status would be better in future
- future enhancement
- start changing proguard rules and verifying app still runs
- #16635
- also do APK inspection (Android Studio has a good tool) which can help find ridiculous things
- anyone can pick this up after #16635 merges

Additionally, may make sense to examine Anki-Android-Backend, there are some thoughts on a previous effort #8473
- anyone can pick this up if they like