io.github.divverent.aaaaxy: migrate to split APKs

Migrating AAAAXY to use split APKs ("Multiple apks for native code"), now that this is supported on F-Droid and necessary build infrastructure is in AAAAXY's latest release.

AAAAXY issue: https://github.com/divVerent/aaaaxy/issues/215

Based on other work on this F-Droid issue: #2809 (closed)

Required

• The app complies with the inclusion criteria
• All related fdroiddata and RFP issues have been referenced in this merge request
• Builds with fdroid build

Strongly Recommended

• The upstream app source code repo contains the app metadata (summary/description/images/changelog/etc) in a Fastlane or Triple-T folder structure
• Releases are tagged

Suggested

• External repos are added as git submodules instead of srclibs
• Multiple apks for native code