arch: split :common:android from :common

[david-allison]

Note

Assisted-by Claude Opus 4.6 (Max Effort)
the initial move was performed and the dependencies were added
But, most were incorrect, so there was a lot of manual fixups

Purpose / Description

I want libanki to become a java-library. Since it depends on :common, :common also needs to be a Java library

Approach

• prep for splitting out common:android:
  • Move to SLF4J, to remove the android dependency
    • We already have transitive dependencies on this, and Timber works out-the-box
  • Fixup a hack regarding opt-in jvm flags
  • Fixup test dependencies to switch Android calls with JVM calls
• Then split out the module

How Has This Been Tested?

app still runs as expected.

Learning (optional, can help others)

I've seen a lot about SLF4J , but never used it. Very easy!

Checklist

• You have a descriptive commit message with a short title (first line, max 50 chars).
• You have commented your code, particularly in hard-to-understand areas
• You have performed a self-review of your own code
• UI changes: include screenshots of all affected screens (in particular showing any new or changed strings)
• UI Changes: You have tested your change using the Google Accessibility Scanner

[mikehardy]

LGTM - carefully changing the engines on the plane while it's aloft, nice

Related - purge the boilerplate out of the new build gradle file in an on-deck-but-next-version PR that also LGTM:

• #20778